Navigation support device, information processing method, and program

Abstract

To more smoothly perform ship navigation.SOLUTION: A navigation support device has: a first determination part for determining a first course that is a course enabling navigation with respect to a second navigation disturbance zone generated in a case where a course of a counter ship is veered at a first angle as a course of own ship, when there is the course of the own ship with respect to a first navigation disturbance zone indicating a collision risk-generating area, and there is a relation of meeting of the counter ship with respect to the own ship or a relation between meeting and crossing of the counter ship with respect to the own ship; a second determination part for determining the course of the own ship as a second course that is a course toward a third navigation disturbance zone, when the own ship is navigated onto the first course based on the first course until reaching the third navigation disturbance zone generated in a case where the course of the counter ship is veered at a second angle larger than the first angle; and a third determination part for determining the course of the own ship as a third course that is a course in an azimuth direction toward a destination, when a veering angle in a case of veering with respect to the destination of the own ship is smaller than an angle toward the second course.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a navigation support device, an information processing method, and a program. [Background technology]

[0002] In recent years, there have been navigation support systems that display the risk of collision between one's own ship and another ship in a comprehensible manner. For example, there is a system that performs collision calculations between one's own ship and another ship, and displays an Obstacle Zone by Target (OZT) based on the results of the collision calculations (for example, Patent Document 1). In such a system, when a navigation interference zone is displayed, navigators can specifically grasp the area in which they need to be careful. Also, if navigators steer their vessel to avoid the displayed navigation interference zone, they can navigate without colliding with other vessels. In addition, taking into consideration that the displayed OZT position is unstable due to variations in the measurement results of the ship speed vector used in OZT calculation, there are systems that increase the display size of the circle indicating the OZT (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-095333 A [Patent Document 2] International Publication No. 2020-008776 Summary of the Invention [Problem to be solved by the invention]

[0004] However, even if you refer to the displayed OZT and take evasive action to avoid a collision with the other vessel, if there is a change in the course or speed of the other vessel, the OZT will also change. In that case, the vessel's navigator must determine whether or not it is necessary to change the vessel's current course or speed after the displayed OZT has changed. In addition, because the OZT display changes every time there is a change in the other vessel's behavior, the vessel's navigator must determine whether or not it is necessary to change the vessel's course, etc., each time, which places a burden on the vessel's maneuvering. If the OZT display size is increased to take into account the variability in the actions of other ships, it may be difficult to distinguish this from a situation where there is no variability, and this may result in the ship having to take larger than necessary avoidance actions. In addition, simply avoiding the OZT may not always convey the ship's intention to avoid the collision to the other ship. In such cases, it is difficult to alleviate the anxiety of the other ship's operator about the risk of collision, making it difficult to reassure them.

[0005] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a navigation support device, an information processing method, and a program that can facilitate smoother ship navigation. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, one aspect of the present invention includes a first determination unit that determines, as the course of the first ship, a first course that is an avoidable course for a second interference zone that occurs when the course of the other ship changes course by a first angle when the course of the other ship is in a first interference zone that indicates an area where a collision risk occurs, and the other ship is in a meeting relationship with the first ship or in a relationship between meeting and crossing the first ship; and a first determination unit that determines, as the course of the first ship, a first course that is an avoidable course for a second interference zone that occurs when the course of the other ship changes course by a first angle when the course of the other ship changes course by a first angle when the course of the other ship changes course by a first angle. The navigation support device has a second determination unit that determines the course of the ship as a second course, which is a course toward the third navigation interference zone, when the ship navigates based on the first course until it reaches a third navigation interference zone that occurs when the ship changes course by a second angle that is the largest, an angle determination unit that determines the relative magnitude between the angle toward the second course and the course change angle when the ship changes course toward the destination of the ship, and a third determination unit that determines the course of the ship as a third course, which is a course in a direction toward the destination, when the course change angle is smaller than the angle toward the second course.

[0007] Moreover, one aspect of the present invention is a navigation support device having a first determination unit that determines a fourth course, which is a course toward the other ship, as the course of the ship of the own ship when the ship's heading is relative to a first navigation interference zone that indicates an area where a risk of collision occurs, which is determined by performing a collision calculation between the ship of the own ship and the other ship, the other ship is in a crossing relationship with the ship of the own ship, and a course that avoids a second navigation interference zone corresponding to an angle rank is greater than the bearing of the other ship, an angle determination unit that determines the relative magnitude between the angle toward the fourth course and a course change angle if the ship changes course to its destination, and a third determination unit that determines the course of the ship of the own ship as a fifth course, which is a course toward the destination, when the course change angle is smaller than the angle toward the fourth course.

[0008] In one aspect of the present invention, a first determination unit determines, as a course of the first ship, a first course that is an avoidable course for a second interference zone that occurs when the course of the other ship changes course by a first angle, when the course of the first ship is in a first interference zone that indicates an area where a collision risk occurs, the first interference zone being determined by performing a collision calculation between the first ship and the other ship, the other ship is in a crossing relationship with the first ship, and a course that avoids a second interference zone corresponding to an angle rank is equal to or less than the bearing of the other ship; and, on the first course, The navigation support device has a second determination unit that causes the ship to navigate based on the first course until the target ship arrives, and when the target ship reaches the first course, determines the course of the ship as a sixth course, which is a course toward the target ship, an angle determination unit that determines the relative magnitude between the angle toward the sixth course and the course change angle if the ship changes course toward the destination, and a third determination unit that determines the course of the ship as a seventh course, which is a course in a direction toward the destination, if the course change angle is smaller than the angle toward the sixth course.

[0009] Moreover, one aspect of the present invention is a navigation support device that outputs a navigation interference zone according to the relationship between one's own ship and another ship, the navigation support device having a fluctuation data supply unit that provides fluctuation data representing the degree of fluctuation in at least one of the course and speed of the other ship to a calculation unit that calculates the navigation interference zone, and an output unit that outputs a navigation interference zone calculated based on the fluctuation data, which is different from the navigation interference zone generated based on the current behavior of the other ship.

[0010] Another aspect of the present invention is an information processing method executed by a computer, in which a first determination unit determines, as the course of the first ship, a first course that is an avoidable course for a second navigation interference zone that occurs when the course of the other ship changes course by a first angle when the course of the first ship is in a first navigation interference zone that indicates an area where a collision risk occurs, and the other ship is in a meeting relationship with the first ship or in a relationship between meeting and crossing with the first ship, and a second determination unit determines, on the first course, This is a navigation support method in which, when the ship navigates based on the first course until it reaches a third navigation interference zone that occurs when the other ship's course changes course by a second angle greater than the first angle, the course of the ship is determined to be a second course, which is a course toward the third navigation interference zone, an angle determination unit determines the magnitude relationship between the angle toward the second course and the course change angle when the ship changes course toward its destination, and a third determination unit determines the course of the ship to be a third course, which is a course in a direction toward the destination, if the course change angle is smaller than the angle toward the second course.

[0011] Moreover, one aspect of the present invention is an information processing method executed by a computer, in which a first determination unit determines a fourth course, which is a course toward the other ship, as the course of the ship of the own ship when the ship's heading is relative to a first navigation interference zone indicating an area where a risk of collision occurs, which is determined by performing a collision calculation between the ship of the own ship and the other ship, the other ship is in a crossing relationship with the ship of the own ship, and a course that avoids a second navigation interference zone corresponding to an angle rank is greater than the bearing of the other ship, an angle determination unit determines the magnitude relationship between the angle toward the fourth course and the course change angle if the ship changes course to its destination, and a third determination unit determines the course of the ship of the own ship as a fifth course, which is a course toward the destination, when the course change angle is smaller than the angle toward the fourth course.

[0012] Another aspect of the present invention is an information processing method executed by a computer, in which a first decision unit determines, when the course of the first ship is relative to a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the first ship and the other ship, the other ship is in a crossing relationship with the first ship, and a course that avoids a second navigation interference zone corresponding to an angle rank is equal to or less than the bearing of the other ship, a first course that is an avoidable course for the second navigation interference zone that occurs when the course of the other ship changes course by a first angle is determined as the course of the first ship. a second determination unit causes the ship to navigate based on the first course until the other ship reaches the first course, and when the other ship reaches the first course, determines the course of the ship as a sixth course which is a course toward the other ship; an angle determination unit determines which is larger between the angle toward the sixth course and the course-changing angle if the ship changes course toward its destination; and a third determination unit determines, if the course-changing angle is smaller than the angle toward the sixth course, the course of the ship as a seventh course which is a course in a direction toward the destination.

[0013] Another aspect of the present invention is an information processing method executed by a computer that outputs a navigation interference zone according to the relationship between the own ship and another ship, the information processing method including providing fluctuation range data representing the degree of fluctuation in at least one of the course and speed of the other ship to a calculation unit that calculates the navigation interference zone, and outputting a navigation interference zone calculated based on the fluctuation range data, which is different from a navigation interference zone generated based on the current behavior of the other ship.

[0014] In one aspect of the present invention, when the course of the first ship is relative to a first navigation interference zone indicating an area where a collision risk occurs, which is calculated by having a computer perform a collision calculation between the first ship and the other ship, and the other ship is in a meeting relationship with the first ship or in a relationship between meeting and crossing with the first ship, a first course is determined as the course of the first ship, which is a course that can avoid a second navigation interference zone that occurs when the course of the other ship changes course by a first angle, and a first course is determined as the course of the first ship, and the course of the other ship is calculated by performing a collision calculation between the first ship and the other ship, and when the course of the other ship changes course by a first angle, a first course is determined as the course of the first ship, which is a course that can avoid a second navigation interference zone that occurs when the course of the other ship changes course by a first angle. When the ship navigates based on the first course until it reaches a third interference zone that would occur if the ship were to change course by a second angle greater than 10 degrees, the program determines the course of the ship as a second course, which is a course toward the third interference zone, determines the magnitude relationship between the angle toward the second course and the course change angle if the ship were to change course toward the ship's destination, and if the course change angle is smaller than the angle toward the second course, determines the course of the ship as a third course, which is a course in a direction toward the destination.

[0015] Moreover, one aspect of the present invention is a program that causes a computer to execute the following: when the ship's heading is relative to a first navigation interference zone indicating an area where a risk of collision occurs, which is determined by performing a collision calculation between the ship and the other ship, the other ship is in a crossing relationship with the ship, and a heading that avoids a second navigation interference zone corresponding to an angle rank is greater than the bearing of the other ship, determine a fourth course, which is a course toward the other ship, as the ship's heading; determine a magnitude relationship between the angle toward the fourth course and the course change angle if the ship changes course to its destination; and when the course change angle is smaller than the angle toward the fourth course, determine the ship's heading as a fifth course, which is a course toward the destination.

[0016] In one aspect of the present invention, when the course of the first ship is in a first navigation interference zone indicating an area where a collision risk occurs, which is calculated by a computer performing a collision calculation between the first ship and the other ship, the other ship is in a crossing relationship with the first ship, and a course that avoids a second navigation interference zone corresponding to an angle rank is equal to or less than the bearing of the other ship, the first course, which is a course that can avoid the second navigation interference zone that occurs when the course of the other ship changes course by a first angle, is determined as the course of the first ship, The program causes the ship to navigate based on the first course until the other ship reaches the first course, and when the other ship reaches the first course, determines the course of the ship as the sixth course, which is a course toward the other ship, determines the magnitude relationship between the angle toward the sixth course and the course change angle if the ship changes course toward its destination, and if the course change angle is smaller than the angle toward the sixth course, determines the course of the ship as the seventh course, which is a course in a direction toward the destination.

[0017] Another aspect of the present invention is a program that causes a computer to output a navigation interference zone based on the relationship between the own ship and another ship to provide fluctuation range data representing the degree of fluctuation in at least one of the course and speed of the other ship to a calculation unit that calculates the navigation interference zone, and output a navigation interference zone calculated based on the fluctuation range data that is different from the navigation interference zone generated based on the current behavior of the other ship. Effect of the Invention

[0018] As described above, according to the present invention, it is possible to grasp the navigation interference zone according to the change in the behavior of the other ship, thereby making it possible to more smoothly navigate the ship. Furthermore, the present invention can reduce the anxiety of the operator of the other ship regarding the risk of collision, thereby increasing the sense of security when navigating, and thus making the navigation of the ship smoother. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic block diagram showing a configuration of a system in which a navigation support device according to an embodiment of the present invention is used. [Diagram 2] FIG. 11 is a diagram for explaining a case where OZT changes in response to a change in the behavior of the other ship. [Diagram 3] 4 is a flowchart illustrating the operation of the navigation support device 20. [Figure 4] FIG. 13 is a diagram showing an example of a display screen when an OZT obtained based on calculation method A is displayed. [Diagram 5] FIG. 13 is a diagram showing an example of a display screen when an OZT obtained based on calculation method B is displayed. [Figure 6] FIG. 13 is a diagram showing an example of a display screen when an OZT obtained based on calculation method B is displayed. [Figure 7] FIG. 13 is a diagram showing an example of a display screen when an OZT obtained based on calculation method B is displayed. [Figure 8] FIG. 13 is a diagram showing an example of a display screen when an OZT obtained based on calculation method B is displayed. [Figure 9] FIG. 13 is a diagram showing an example of a display screen when an OZT obtained based on calculation method B is displayed. [Figure 10A] FIG. 13 is a diagram showing an example of a display screen when an OZT obtained based on calculation method B is displayed. [Figure 10B] This diagram was used to compare OZT when the ship's speed is different. [Figure 10C] This diagram was used to compare OZT when the ship's speed is different. [Figure 11] FIG. 13 is a diagram showing an example of a display screen when an OZT obtained based on calculation method B is displayed. [Figure 12] FIG. 13 is a diagram showing an example of a display screen when an OZT obtained based on calculation method B is displayed. [Figure 13] FIG. 11 is a schematic block diagram showing the configuration of a system in which a navigation support device according to a second embodiment is used. [Figure 14] FIG. 13 is a diagram showing an example of a route when following a vehicle; [Figure 15] FIG. 1 is a diagram illustrating a matchmaking relationship. [Figure 16] 11 is a graph illustrating an example of angle rank data. [Figure 17] 4 is a flowchart illustrating the operation of the navigation support device 20A. [Figure 18] FIG. 13 is a diagram showing an example of a case where LOPC is calculated. [Figure 19] FIG. 1 is a diagram illustrating an example of a LOPC. [Figure 20] FIG. 1 is a diagram illustrating an example of a LOPC. [Figure 21] FIG. 1 is a diagram illustrating an example of a LOPC. [Figure 22] This is a diagram explaining a crossing ship whose matchmaking relationship is similar to that of a meeting ship. [Diagram 23] This is a diagram explaining a crossing ship whose matchmaking relationship is similar to that of a meeting ship. [Figure 24] This is a diagram explaining a crossing ship whose matchmaking relationship is similar to that of a meeting ship. [Diagram 25] 13 is a flowchart illustrating a route generation process for a meeting. [Figure 26] FIG. 13 is a diagram for explaining the process in which the first determination unit 242 determines a course in the case of a crossing ship close to an encounter ship. [Figure 27] FIG. 13 is a diagram showing the relationship between own ship O and other ship T at time t2 after a certain time has elapsed since the processing of step S301. [Figure 28] FIG. 13 is a diagram showing the relationship between own ship O and other ship T at time t3 after a certain time has elapsed since the processing of step S302. [Figure 29] FIG. 13 is a diagram showing the relationship between own ship O and other ship T at time t4 after a certain time has elapsed since the processing of step S304. [Diagram 30] 13 is a flowchart illustrating a route generation process by tracking. [Diagram 31]FIG. 13 is a diagram for explaining the process in which the first determination unit 242 determines a course in relation to a crossing ship (obligation to give way). [Diagram 32] FIG. 13 is a diagram showing the relationship between own ship O and other ship T at time t2 after a certain time has elapsed since the processing of step S401. [Diagram 33] FIG. 13 is a diagram showing the relationship between own ship O and other ship T at time t3 after a certain time has elapsed since the processing of step S402. [Diagram 34] 13 is a flowchart illustrating a route generation process for irregular tracking. [Diagram 35] FIG. 13 is a diagram for explaining the process in which the first determination unit 242 determines a course in relation to a crossing ship (obligation to give way). [Diagram 36] FIG. 13 is a diagram showing the relationship between own ship O and other ship T at time t2 after a certain time has elapsed since the processing of step S501. [Figure 37] FIG. 13 is a diagram showing the relationship between own ship O and other ship T at time t3 after a certain time has elapsed since the processing of step S502. [Figure 38] FIG. 13 is a diagram showing the relationship between own ship O and other ship T at time t4 after a certain time has elapsed since the processing of step S503. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] First Embodiment FIG. 1 is a schematic block diagram showing the configuration of a system in which a navigation support device according to an embodiment of the present invention is used. The navigation management system 10 and the navigation support device 20 are communicatively connected. The navigation management system 10 is, for example, a sensor such as a radar (TT; Target Tracking), an Automatic Identification System (AIS; Automatic Identification System), a gyro (GYRO), a ship speed and distance meter, etc. The navigation management system 10 supplies the results obtained from the various sensors to a navigation support device 20. These include an Electronic Chart Display and Information System (ECDIS), a marine radar device, etc.

[0021] The navigation support device 20 may be a computer, or may be incorporated as a module in a radar or ECDIS, or the output of the navigation support device 20 may be displayed on a radar or ECDIS. In addition, the functions of the navigation support device 20 may be realized by being installed and executed on a portable terminal device such as a smartphone or a tablet as application software that realizes the functions of the navigation support device 20. Such a navigation support device 20 is mounted on a ship.

[0022] The navigation support device 20 has a function of calculating a collision zone by a target ship (OZT) based on the relationship between the ship and the target ship, and outputting the obstacle zone. The obstacle zone indicates an area where there is a risk of collision between the ship and the target ship. Collision calculation is a calculation of whether or not your ship will collide with the other ship based on various information about the other ship and the other ship (position, speed, direction of travel, etc.) and the safe passing distance. In this embodiment, in addition to collision calculation based on the current behavior of the other ship (speed, course, etc.), we will explain how collision calculation is also performed assuming that the behavior of the other ship changes (fluctuations).

[0023] The navigation support device 20 includes an input unit 210 , an amplitude width data calculation unit 220 , an amplitude width data supply unit 230 , an arithmetic unit 240 , an output unit 250 , and a memory unit 260 . The input unit 210 acquires various data. For example, the input unit 210 acquires results obtained from various sensors in the navigation management system 10 from the navigation management system 10. The results obtained from the various sensors include, for example, data indicating the position, speed, and course of the other ship as information necessary for calculating the navigation interference zone.

[0024] The fluctuation amplitude data calculation unit 220 generates fluctuation amplitude data indicating the amplitude of fluctuation according to the changes in the behavior of the other ship. The fluctuation range in response to changes in the other vessel's behavior may be any data that enables the degree of change to be grasped, in relation to the other vessel's current behavior (course, speed, etc.). For example, when grasping changes in the other vessel's behavior based on speed, it can be expressed as the fluctuation range (variation range) of speed, and specifically, it may be the percentage change in speed (2% increase, 3% decrease, etc.) or the difference in speed change (1 knot increase, 2 knot decrease, etc.).

[0025] When determining changes in the behavior of another ship based on its course, this can be expressed as the deviation (variation) of the course, and specifically, the angle by which the course was changed (-3°, +5°, etc.).

[0026] There are various factors that can cause changes in the behavior of the other ship, such as (1) the other ship's swaying, (2) measurement errors, etc.

[0027] (1) Regarding the other vessel's sway If the other vessel is maintaining its speed and course, and your vessel is also maintaining its speed and course, the calculated OZT will not fluctuate significantly with time. However, if there is a change in the other vessel's speed or course, the calculated OZT will fluctuate. Changes in the other vessel's speed or course can occur when the other vessel's navigator steers the vessel to change its speed or course, or when the other vessel is affected by weather and sea conditions (external forces) such as waves, wind, and currents, and is unable to maintain its speed or course.

[0028] (2) Measurement errors Measurement results obtained from various sensors may contain measurement errors, for example, results measured by radar may have an error of about ±3° for course over ground (COG) and ±5% for speed over ground (SOG). When measurement errors are included in the observation data, even if the other ship is actually able to maintain its speed and course, the observation data will fluctuate, and it can be interpreted as a change in the behavior of the other ship.

[0029] Here, Figure 2 is a diagram explaining a case where OZT changes in response to a change in the behavior of the other ship. Figure 2 is quoted from Figure 4 in the reference (Tamaru Hitoshi, Nishizaki Chihiro, Kayano Jun, Imazu Junma: Basic Study on the Construction of Collision Avoidance Algorithm Using OZT Distribution, Journal of the Japan Institute of Navigation, Vol. 139, p. 1-9, 2018). This Figure 2 shows an example of a case where OZT calculated by performing a collision calculation is displayed on a screen showing the positions of the own ship and the other ship based on data obtained by AIS. Here, a total of seven observations were made at 30 second intervals over a three minute period, and the OZT calculated each time an observation result was obtained and the position of each ship are shown. Here, when the ship S0 moves in the lower left direction on the drawing as indicated by the arrow A1, figures (circles) indicating the ship's position obtained at 30 second intervals are displayed in a row on the lower left.

[0030] OZT is required for the targets Sb, Sc, Sd, Se, Sf, Sg, Sh, Si, and Sj among the targets Sb to So. The OZT of each of the target ships Sb, Se, and Sg has hardly changed its position (relative to the ground). Here, it can be said that there has been almost no change in the behavior of these target ships Sb, Se, and Sg (speed, course, etc. are being maintained).

[0031] The OZT of each of the target ships Sc, Sd, Sf, and Sh changes because the position of the OZT is different each time the position (relative to the ground) is observed. Here, the behavior of the target ships Sc, Sd, Sf, and Sh changes, and the OZT also changes to vary with this change in behavior. For example, the OZT of the target ship Sd varies so that the distance and direction to the OZT are different when viewed from the position of the target ship Sd, as shown by the symbol B1. In this way, when the position of the OZT changes, it can be said that the position where the risk of collision occurs changes.

[0032] For the other ships Si and Sj, OZT was obtained in several of the seven observations. In this case, when a collision calculation was performed based on the observation results at one point in time, OZT was not obtained, but when a collision calculation was performed based on the observation results at another point in time, OZT was obtained, so it can be said that the state switched between when there was a risk of collision and when there was no risk of collision.

[0033] When the OZT position does not change much, the burden of attention on the ship's operator is relatively low, since the positions that need attention to avoid collision risks do not change much, which can be said to be about the same level of attention as when avoiding fixed obstacles.

[0034] On the other hand, if the other ship drifts or there is a measurement error, the OZT position will change. In this case, the ship's navigator must steer the ship while taking into consideration not only the OZT calculated based on the current observation results of the other ship, but also any changes in the other ship's behavior. For example, even if a ship's course is determined and navigated based on the OZT displayed based on observation data obtained at a certain moment, if the other ship sways or a measurement error occurs, the position of the OZT will also change. If this happens, the changed position of the OZT may interfere with the ship's course. In this case, the risk of collision can be avoided by changing the ship's course so that it does not interfere with the OZT, but the position of the OZT displayed based on observation data obtained at the next timing may interfere with the ship's course. This may result in the ship being unable to maneuver smoothly.

[0035] In addition, for other ships (e.g., other ships Si, Sj, etc.) for which OZT may or may not be available, even if OZT is not obtained as a result of performing a collision calculation based on observation data at a certain timing, if OZT is obtained at a later timing due to the other ship's swaying, etc., that OZT may interfere with the course of the ship. Furthermore, if OZT is not obtained at a later timing due to the other ship's swaying, etc., that OZT will not be displayed. In this way, when OZT is repeatedly obtained and not obtained, even if OZT is no longer displayed, the ship must remember the position of the OZT and steer assuming that it will be displayed again, so the burden of paying attention is greater than when the behavior of the other ship does not change much.

[0036] In this embodiment, in addition to outputting the OZT obtained based on the current observation results of the other ship on the display screen, the OZT is calculated for the case where the other ship's behavior is assumed to have changed, and output it on the display screen. This allows the ship's navigator to check the OZT when the other ship's behavior has changed, and since the ship's navigator can steer the ship while taking this OZT into consideration, the ship's navigator does not have to think about how the OZT will change when the other ship's behavior changes, which reduces the burden on the ship's navigator.

[0037] Returning to FIG. 1, the fluctuation width data calculation unit 220 can determine the degree of change in the behavior of the other ship from the tendencies of the other ship's past behavior in any manner, but can, for example, determine the degree of change in the behavior of the other ship as follows.

[0038] (Calculation method A) Degree of change based on past behavioral trends The fluctuation data calculation unit 220 determines the degree of change in the behavior of the other ship from the trends in the other ship's past behavior. More specifically, the fluctuation data calculation unit 220 determines the average value and standard deviation of the course or speed based on the trends in the other ship's past movements. The fluctuation data calculation unit 220 outputs the average value and standard deviation of the course or speed to the fluctuation data supply unit 230 as fluctuation data representing the degree of change in behavior (fluctuation range). When calculating the fluctuation data based on the average course (COG) and standard deviation, the fluctuation data calculation unit 220 calculates the average course (COG) value (Ave) from the COG of the other ship for the past n minutes (for example, 1 minute) as shown in the following formulas (1) and (2). COG ) and standard deviation (σ COG ) is calculated. Here, the fluctuation of COG is assumed to follow a normal distribution. Ave COG +2σ COG (1) Ave COG -2σ COG (2) Here, the swing width data calculation unit 220 supplies the values ​​obtained by equations (1) and (2) as swing width data to the collision calculation unit 241. As a result, the collision calculation unit 241 calculates two OZTs as the second navigation interference zone: an OZT based on the swing width data obtained by equation (1) and an OZT based on the swing width data obtained by equation (2).

[0039] In addition, when calculating the fluctuation data based on the average speed (SOG) and the standard deviation, the fluctuation data calculation unit 220 calculates the average speed (Ave) from the SOG of the other ship for the past n minutes (for example, 1 minute) as shown in the following formulas (3) and (4). SOG ) and standard deviation (σ SOG) is calculated. Here, the fluctuation of SOG is assumed to follow a normal distribution. Ave SOG +2σ SOG (3) Ave SOG -2σ SOG (4) Here, the swing width data calculation unit 220 supplies the values ​​obtained by equations (3) and (4) as swing width data to the collision calculation unit 241. As a result, the collision calculation unit 241 calculates two OZTs as the second navigation interference zone: an OZT based on the swing width data obtained by equation (3) and an OZT based on the swing width data obtained by equation (4).

[0040] Here, of the course and the speed of a ship, the course tends to fluctuate more easily due to the influence of disturbances, etc. Therefore, although the fluctuation data may be obtained for both the course and the speed, the fluctuation data may be obtained for the course only.

[0041] When calculating OZT based on calculation method A, it is possible to obtain an OZT that takes into account cases where external disturbances have caused variations in the course or speed of the other ship. For example, due to external disturbances such as errors or the effects of waves, observation data at a certain point in time may deviate significantly from multiple other observation data, and the OZT calculated based on that observation data may also deviate significantly from the OZT that would be obtained without the disturbances. Therefore, by using the statistical values ​​of observation data obtained over the past n minutes, even if observation data with momentary variability is obtained, it is possible to calculate an OZT (second navigation interference zone) that takes variability into account, taking into account the past trends of the other ship, so that the OZT does not deviate significantly. When calculating the OZT based on calculation method A, the second interference zone may be calculated using the maximum deviation value in the past n minutes.

[0042] (Calculation method B) Predetermined range The swing data calculation unit 220 determines at least one angle that indicates the course when a change occurs with respect to the current course of the other ship. For example, the swing data calculation unit 220 may determine several angles according to an arbitrary increment as the angle that indicates the course when a change occurs, and specifically, may determine angles at predetermined increments (for example, 5°) within a certain angle range (for example, ±30°) based on the current course of the other ship. This angle range may be any range other than ±30°, such as ±20°, ±35°, etc. Also, the increment may be 2°, 10°, etc. other than 5°. The swing data calculation unit 220 determines the angle by extracting at least one angle according to a predetermined increment (for example, 5°) from a certain angle range (for example, ±30°) based on the current course of the other ship. For example, the fluctuation range data calculation unit 220 extracts angles of -20°, -15°, -10°, -5°, 5°, 10°, 15°, and 20°, and outputs these angles to the fluctuation range data supply unit 230 as fluctuation range data representing the degree of change in behavior (fluctuation range).

[0043] Such angle ranges and increments may be determined in advance, or may be specified by the input unit 210 and determined by the swing data calculation unit 220 based on the specified ranges and increments. When using calculation method B, the swing data calculation unit 220 may determine the swing data regardless of the tendency of the other ship's past behavior. In addition, the amplitude data calculation unit 220 may determine in advance which of calculation method A and calculation method B to use, or may calculate according to a calculation method according to a selection instruction for selecting a mode input from the input unit 210.

[0044] The fluctuation width data supply unit 230 acquires fluctuation width data that indicates the degree of fluctuation in at least one of the course and speed of the other ship from the fluctuation width data calculation unit 220 and supplies it to a collision calculation unit 231 of the operation unit 240.

[0045] The calculation section 240 performs various calculations based on the data obtained from the input section 210 or the amplitude data supply section 230, and outputs the calculation results via the output section 250, thereby causing the display device to display various data. The calculation unit 240 can be configured by a processing device such as a CPU (Central Processing Unit) or a dedicated electronic circuit.

[0046] The calculation unit 240 has the function of a collision calculation unit 241 . The collision calculation unit 241 performs collision calculations to determine whether or not the ship will collide with the other ship based on various data obtained from the navigation management system 10, and calculates OZT. OZT is determined according to the current course of the ship, the current course of the other ship, and the speed ratio between the other ship and the ship. There are several methods for calculating OZT when performing collision calculations, but in this embodiment, a case where OZT is calculated based on a method called "line segment OZT" will be described. The line segment OZT method is one of the general calculation methods for calculating OZT, and the collision calculation unit 241 can calculate OZT according to the general line segment OZT method when calculating OZT.

[0047] The collision calculation unit 241 performs collision calculations based on the current observation results for the other ship input from the input unit 210, and calculates the OZT as a first navigation interference zone. The collision calculation unit 241 also performs collision calculations based on the amplitude data supplied from the amplitude data supply unit 230, and calculates the OZT as a second navigation interference zone.

[0048] The output unit 250 outputs data to a display device. For example, in the case where a display device is provided in the navigation support device 20, the output unit 250 outputs data to the display device to display various data. The output unit 250 may also output data to an electronic chart information display device or a marine radar device to display various data on the electronic chart information device or the marine radar device. For example, the output unit 250 may display the navigation interference zone determined by the calculation unit 240 in a manner superimposed on the display area in which the radar screen is displayed, or may display the navigation interference zone in a display area adjacent to the radar screen. The output unit 250 may also switch the navigation interference zone between a hidden state and a displayed state in response to an instruction input from an operator.

[0049] The output unit 250 can output not only the first navigation interference zone but also the second navigation interference zone. That is, the output unit 250 outputs a navigation interference zone calculated based on the amplitude data, which is different from the navigation interference zone generated based on the current behavior of the other ship. Here, the output unit 250 displays the first navigation interference zone and the second navigation interference zone with different line segments. The current behavior of the other ship may be the behavior of the other ship at the same time when the amplitude data calculation unit 220 calculates the amplitude data, or may be behavior based on observation data of the other ship obtained within a certain time (e.g., several seconds, tens of seconds, etc.) from the time when the amplitude data calculation unit 220 calculates the amplitude data. That is, it may be the behavior of the other ship within a certain time that can be considered as the current behavior. When displaying the second navigation interference zone, the output unit 250 displays the second navigation interference zone on the display screen in a display manner different from that of the first navigation interference zone. The different display manner may be the thickness of the line representing the OZT, the type of line (solid line, dashed line, dashed line, etc.), the color of the line, etc. The output unit 250 displays the auxiliary data indicating the amplitude data used to determine the second navigation interference zone near the position where the second navigation interference zone is displayed. For example, when the amplitude data indicates a course change, the auxiliary data may be an angle such as "-5°" or "10°".

[0050] The storage unit 260 stores various data. The storage unit 260 may store computer programs for implementing the functions of the swing width data calculation unit 220, the swing width data supply unit 230, and the collision calculation unit 231, and the calculation unit 240 may read and execute the computer programs to implement the function of outputting a navigation interference zone based on the swing width data. The memory unit 260 is configured with a storage medium, for example, a hard disk drive (HDD), a flash memory, an electrically erasable programmable read only memory (EEPROM), a random access read / write memory (RAM), a read only memory (ROM), or any combination of these storage media. The storage unit 260 may be, for example, a non-volatile memory.

[0051] Next, a description will be given of the operation of the above-mentioned navigation support device 20. FIG. The input unit 210 of the navigation support device 20 acquires various data from the navigation management system 10 (step S101). The data acquired here includes, for example, the speed of the own ship, the speed of the other ship, the position of the own ship, the position of the other ship, the course of the own ship, the course of the other ship, and the safe passing distance. The safe passing distance is determined based on the distance at which a vessel can safely pass the closest distance to the other vessel (DCPA; Distance of CPA).

[0052] When various data are input to the input unit 210, the calculation unit 240 determines a first navigation interference zone based on the various input data by the collision calculation unit 241 (step S102). When various data are input to the input unit 210, the fluctuation width data calculation unit 220 calculates fluctuation width data (step S103) and supplies the calculated fluctuation width data to the collision calculation unit 241 (step S104). For example, when based on calculation method A, the fluctuation width data calculation unit 220 generates fluctuation width data based on an average value and a standard deviation and supplies it to the collision calculation unit 241. When based on calculation method B, the fluctuation width data calculation unit 220 generates fluctuation width data indicating a range of fluctuation and an increment width and supplies it to the collision calculation unit 241. The collision calculation unit 241 determines the second navigation interference zone based on the supplied swing width data (step S105). The output unit 250 displays the first and second navigation interference zones calculated by the collision calculation unit 241 on a display screen (step S106). The process shown in this flowchart is executed every time a certain period of time elapses, for example, every time various data are obtained from the navigation management system.

[0053] FIG. 4 is a diagram showing an example of a display screen when the OZT obtained based on the calculation method A is displayed. In this diagram, a first navigation interference zone OZT and multiple second navigation interference zones are displayed on the course of the own ship Sa as navigation interference zones between the opposing ship Sb and the first navigation interference zone OZT. The line thickness of the first navigation interference zone OZT is displayed in a manner that is thicker than the multiple second navigation interference zones. The second navigation interference zones include a navigation interference zone OZTc1 and a navigation interference zone OZTc2 obtained based on the average value and standard deviation of the COG. The navigation interference zone OZTc1 is located closer to the ship than the OZT position, and the navigation interference zone OZTc2 is located farther away from the ship than the OZT position. The second navigation interference zones include a navigation interference zone OZTs1 and a navigation interference zone OZTs2, which are OZTs obtained based on the average value and standard deviation of the SOG. The navigation interference zone OZTs1 is located closer to the ship than the OZT position, and the navigation interference zone OZTs2 is located farther away from the ship than the OZT position.

[0054] FIG. 5 is a diagram showing an example of a display screen when the OZT obtained based on the calculation method B is displayed. In this figure, the result of calculating OZT is shown when the own ship Sa and the other ship Sb are in an encounter relationship and both are traveling at a speed of 12 knots. Also, in this figure, the case where the deviation data calculation unit 220 has determined that the step size is ±3% (two deviation data of -3% and +3%) with respect to the course obtained as the current observation data is shown. The first interference zone is displayed by a solid line, and the second interference zone is displayed by a dashed line, and the first interference zone and the second interference zone are displayed in different display modes. Also, a concentric circle scale is displayed with the own ship Sa at the center. The first navigation interference zone OZT exists between the first ship Sa and the other ship Sb, and the second navigation interference zone OZTc1 and the second navigation interference zone OZTc2 are roughly in the same position as between the first ship Sa and the other ship Sb, but the positions of the ends of the OZT are different. The length of the second navigation interference zone OZTc1 is longer than the first navigation interference zone OZT, and the second navigation interference zone OZTc2 is shorter than the first navigation interference zone OZT. By referring to this display screen, the ship helmsman can steer the ship while checking on the screen that if the course of the other ship Sb begins to deviate, the position of the OZT obtained based on the current observation data will generally remain the same, but there is a possibility that its length may become longer or shorter.

[0055] 6 and 7 are diagrams showing examples of a display screen when the OZT obtained based on the calculation method B is displayed. Fig. 6 shows a case where OZT is calculated when the other ship Sb is in a crossing relationship with the first ship Sa, the speed of the other ship Sb is 18 knots, and the speed of the first ship Sa is 12 knots (the other ship Sb is a high-speed ship). Figs. 6 and 7 also show a case where the fluctuation range data calculation unit 220 has determined that the step size is ±3% (two fluctuation range data of -3% and +3%) with respect to the course obtained as the current observation data.

[0056] Figure 6 illustrates a case where the OZT transitions from a displayed state to a not displayed state when there is a change in the course of the other ship Sb, and Figure 7 illustrates a case where the OZT transitions from a not displayed state to a displayed state when there is a change in the course of the other ship Sb. In FIG. 6, the OZT obtained based on the current observation data of the target ship Sb is displayed as the navigation interference zone OZT. The OZT when the target ship Sb's course changes by -3° is displayed as the second navigation interference zone OZTc1. In addition, the character string "-3°" is displayed as auxiliary data near the second navigation interference zone OZTc1. This character string is the amplitude data (step width) used to determine the second navigation interference zone. By displaying such auxiliary data together with the second navigation interference zone OZTc1, it is possible to understand the degree of change in the current course of the target ship Sb that may result in the OZT.

[0057] On the other hand, the OZT in the case of "+3°" is not displayed. This indicates that if the course of the other ship Sb changes by +3°, the OZT cannot be obtained (OZT does not occur). As a result, the navigator can not only grasp the position of the OZT when the course of the other ship Sb changes by -3°, but also grasp that the OZT will disappear when the course of the other ship Sb changes by +3°. This reduces the burden during maneuvering because it is possible to grasp that the OZT may disappear depending on the course of the other ship Sb while the current OZT is displayed. In addition, the OZT according to the current course of the other ship Sb may disappear depending on the course of the other ship Sb, but it can also be grasped that the OZT is near the boundary where the OZT will be displayed again depending on the subsequent situation (so-called chattering state). In this case, by avoiding the second navigation interference zone OZTc1, the collision risk can be avoided with plenty of time.

[0058] In FIG. 7, when the current course of the first ship Sa is 332° and the current course of the other ship Sb is 315°, the OZT is not obtained, and the first navigation interference zone is not displayed on the screen. In contrast, when the course of the other ship Sb changes by -5° from the current course, the second navigation interference zone OZTc1 is obtained and displayed on the screen. When the course of the other ship Sb changes by -10° from the current course, two OZTs, the second navigation interference zone OZTc21 and the second navigation interference zone OZTc22, are obtained and displayed on the screen. In addition, the character string "-5°" is displayed as auxiliary data near the second navigation interference zone OZTc21, and the character string "-10°" is displayed as auxiliary data near the second navigation interference zone OZTc22. Here, when a collision calculation is performed, the current course of the other ship Sb is outside the LOPC (Line of Predicted Collision), so no OZT occurs. If the other ship Sb changes course by -5° from its current course, the other ship's course will be close to the tangent of the LOPC, so one long OZT will occur. If the other ship Sb changes course by -10° from its current course, it will cross the LOPC, so two OZTs will occur. LOPC will be discussed later.

[0059] In this case, even if the own ship Sa maintains its current course and the OZT is not displayed, if the course of the other ship Sb changes to the left, the OZT will appear, and the collision risk will suddenly increase from no to present. If the other ship Sb returns to its original course, the OZT will disappear, but if the other ship Sb changes its course to the left again, the OZT will appear again, and the collision risk will change from no to present. Therefore, if the own ship Sa only considers the current course of the other ship Sb and does not take any avoiding action, it is not necessarily possible to ensure a safe passing distance from the other ship Sb depending on the state of the other ship Sb's course change.

[0060] In response to this, by calculating the OZT when the current course of the other ship deviates, it is possible to take into account in advance the OZT when a deviation occurs in the current course. This allows the ship to be steered while taking into account avoidance actions, thereby reducing the risk of collision. In addition, if the course of the other ship Sb is changed by -5° and if it is changed by -10°, it is possible to know whether there is one OZT or two OZTs before the course of the other ship Sb is changed, and maneuvering can be carried out taking this into consideration. In this way, when a state in which no collision risk is presented (a state in which the OZT is not displayed) and a state in which the OZT is displayed are repeatedly switched between a state in which there is no collision risk and a state in which there is a collision risk, the burden on maneuvering the ship increases. However, according to this embodiment, a navigation interference zone is determined in advance and displayed taking into account the fluctuating width, so that the repeated switching between a state in which there is a collision risk and a state in which there is no collision risk can be avoided, and the burden on maneuvering can be reduced.

[0061] FIG. 8 is a diagram showing an example of a display screen when the OZT obtained based on the calculation method B is displayed. Fig. 8 illustrates a case where OZT is calculated when the other ship Sb is crossing the own ship Sa. Fig. 8 also illustrates a case where the swing range data calculation unit 220 has determined that the step size is 5° in a range of ±30° with respect to the course obtained as the current observation data of the other ship Sb (a total of 12 swing range data).

[0062] Here, a first navigation interference zone OZT is displayed in front of the own ship Sa, and multiple second navigation interference zones are displayed on the port and starboard sides of the own ship Sa. The second navigation interference zone OZT21 represents the OZT when the target ship Sb changes its current course by +5°, the second navigation interference zone OZT22 represents the OZT when the target ship Sb changes its current course by +10°, the second navigation interference zone OZT23 represents the OZT when the target ship Sb changes its current course by +15°, the second navigation interference zone OZT24 represents the OZT when the target ship Sb changes its current course by +20°, the second navigation interference zone OZT25 represents the OZT when the target ship Sb changes its current course by +25°, and the second navigation interference zone OZT26 represents the OZT when the target ship Sb changes its current course by +30°, and a string of characters indicating the angle of the change is displayed near each OZT as auxiliary data.

[0063] The second navigation interference zone OZT31 represents the OZT when the target ship Sb changes its current course by -5°, the second navigation interference zone OZT32 represents the OZT when the target ship Sb changes its current course by -10°, the second navigation interference zone OZT33 represents the OZT when the target ship Sb changes its current course by -15°, the second navigation interference zone OZT34 represents the OZT when the target ship Sb changes its current course by -20°, the second navigation interference zone OZT35 represents the OZT when the target ship Sb changes its current course by -25°, and the second navigation interference zone OZT36 represents the OZT when the target ship Sb changes its current course by -30°. A string indicating the angle of the change is displayed near each OZT as auxiliary data.

[0064] All of these second interference zones are aligned on the LOPC line calculated when performing collision calculations between own ship Sa and other ship Sb.

[0065] The ship navigator of the own ship Sa can navigate not only by avoiding the first navigation interference zone, but also by using the second navigation interference zone as a clue to anticipate the possibility of the other ship Sb becoming swayed. For example, by navigating to avoid the second navigation interference zone OZTc22, the ship navigator of the own ship Sa can navigate a course that will avoid collision even if the other ship changes course by 10 degrees.

[0066] In this figure, a case has been described in which the second navigation interference zone is determined in a range of ±30° with an increment of 5° (a total of 12 swing data) from the course obtained as the current observation data of the other ship Sb. However, a user such as a ship operator may input the course range and increment for which the second navigation interference zone is determined from the input unit 210, and the swing data calculation unit 220 may determine swing data according to the input content and supply it to the collision calculation unit 241.

[0067] Next, using Figures 9 and 10, it will be explained that the use of the second navigation interference zone enables navigation that takes into account the avoidance ability. Generally, a faster vessel has a higher avoidance ability, and the slower the vessel, the lower the avoidance ability tends to be. For example, when a first vessel is faster than a second vessel, the first vessel can avoid the second vessel with a smaller course-changing angle, whereas when the first vessel is slower than the second vessel, the first vessel can avoid the second vessel with a larger course-changing angle. 9 and 10 are diagrams showing examples of a display screen when the OZT obtained based on the calculation method B is displayed. Figures 9 and 10 show a case in which the other ship Sb is meeting the first ship Sa, the speed of the other ship Sb is 12 knots, and the speed of the first ship Sa is 18 knots, and the first obstruction zone OZT is determined and displayed.

[0068] Also, Figure 9 illustrates a case in which the swing range data calculation unit 220 has determined that the increment width is 5° within a range of ±30° relative to the course obtained as the current observation data of the other ship Sb (a total of 12 swing range data). Here, the first navigation interference zone OZT is displayed in a position aligned in a straight line passing through own ship Sa and the opposing ship Sb, and multiple second navigation interference zones OZTc2a and OZTc2b are also displayed. If the other ship Sb were to change course 15° to port, ship Sa would need to avoid interfering with the second interference zone if the other ship Sb were to change course -15°. In this case, ship Sa needs to avoid interfering with the second interference zone OZTc215, which is -15° out of the second interference zone OZTc2b, to port, so ship Sa only needs to change course 10° to starboard, and the angle of change of course can be smaller than that of the other ship.

[0069] On the other hand, FIG. 10A is a diagram showing a case where the OZT as seen from the other ship Sb is displayed under the same conditions as in FIG. Figure 10A illustrates a case in which the swing range data calculation unit 220 has determined that the increment width is 5° within a range of ±30° relative to the course obtained as the current observation data of the own ship Sa (a total of 12 swing range data). Here, the first navigation interference zone OZT is displayed in a position aligned in a straight line passing through the target ship Sb and own ship Sa, and multiple second navigation interference zones OZTc3a and OZTc3b are also displayed.

[0070] Here, if the first ship Sa changes course 15° to port, the other ship Sb needs to avoid interfering with the second navigation interference zone when the first ship Sa changes course -15°. In this case, the other ship Sb needs to change course 36° to starboard because the second navigation interference zone OZTc315, which is -15° out of the second navigation interference zone OZTc3a, needs to be seen to the port side. In this case, even if the ship to be evaded attempts to take evasive action under the same conditions of a -15° change in course angle, the first ship Sa and the other ship Sb have different speeds, so while the first ship Sa only needs to change course by 10°, the other ship Sb needs to change course by 36°, which requires a large change in course.

[0071] Therefore, by displaying the second obstruction zone on the display device of the ship Sa, the operator of the ship Sa can check the deviation of the other ship Sb in advance and can take evasive action of the ship Sa while considering the speed ratio between the ship Sa and the other ship Sb. In particular, when the ship Sa is faster than the other ship Sb, the ship Sa can take evasive action while considering the deviation of the other ship Sb, and can take evasive action before the other ship Sb changes course due to factors such as disturbances. As a result, the ship Sa can change course more than the first obstruction zone OZT from an early stage, and the angle at which the other ship Sb changes course to take evasive action can be smaller than when the ship Sa is navigating to avoid the first obstruction zone OZT, reducing the burden of evasive action.

[0072] In this way, by displaying the second navigation interference zone on own ship Sa, not only is the risk of collision for own ship Sa reduced, but by own ship Sa taking evasive action at an early stage and larger than the first navigation interference zone (taking evasive action for the second navigation interference zone), the burden of evasive action on the other ship Sb can be reduced. In addition, when the first ship Sa passes through the second navigation interference zone in response to a change in the course of the other ship Sb (for example, -15°) to avoid it, a certain distance is maintained, but when the first ship Sa is faster than the other ship, the psychological burden on the navigator of the first ship Sa (the faster ship) is smaller than when the first ship and the other ship are traveling at the same speed, even if the first ship passes through the same distance. In actual maneuvering, the speed of the ship and the other ship are also taken into consideration when planning an avoidance. For example, when the other ship is passing the bow of a cargo ship (14kt) in a crossing relationship, the ship's altering course angle will be different if the ship is a tanker (14kt) or a container ship (23kt). In other words, even from the ship's point of view, the ship's altering course angle needs to be changed according to the speed ratio. Figures 10B and 10C are cited to compare OZTs when the ship's speed is different. In Figure 10B, the ship's speed is 14 kt, and in Figure 10C, the ship's speed is 23 kt. In Figures 10B and 10C, OZT1 represents the OZT when avoiding another ship by securing a passing distance of 1,800 m in the bow direction. In Figures 10B and 10C, ship Sa can secure a passing distance of 1,800 m in the bow direction by avoiding the left edge of OZT1. In FIG. 10B, the speed of own ship Sa and the other ship Sb is the same, both 14 kt. In this case, even if own ship Sa avoids the left edge of OZT1, OZT2 exists on its course. OZT2 indicates that there is a risk of collision between own ship Sa and the other ship Sb if the other ship changes course 25° to the starboard. Therefore, if the other ship Sb changes course to the starboard, where the collision risk increases, the collision risk remains. In this case, the navigator of own ship Sa may feel the risk of collision. On the other hand, in Figure 10C, the ship Sa is traveling faster than the other ship Sb. In this case, if the ship Sa takes the left edge of OZT1 to avoid collision, there is no OZT on its course. In this case, no matter what angle the other ship Sb changes course to, the ship Sa and the other ship Sb will not collide. Therefore, even if the other ship Sb changes course to the right, there is no risk of collision, so the navigator of the ship Sa is unlikely to feel the risk of collision. In this way, if the speed of the other ship Sb is 14 knots and the speed of the own ship Sa is 23 knots, the other ship Sb's bow can be passed, but if the speed of the own ship Sa is 14 knots, there remains a risk of collision depending on the angle at which the other ship Sb changes course. In this way, even if the safe passing distance is the same 1,800 m, the navigator's perception of it will vary greatly depending on the own ship's speed.

[0073] Next, an evaluation of the effectiveness of the collision avoidance adopted by the own ship Sa (collision avoidance effectiveness) will be described with reference to Figs. 11 and 12. FIG. 11 is a diagram showing an example of a display screen when the OZT obtained based on the calculation method B is displayed. 11 shows a case where the other ship Sb is in an encounter with the first ship Sa, and the navigation interference zones (first navigation interference zone OZT, second navigation interference zone OZTc2a, and second navigation interference zone OZTc2b) seen from the first ship Sa are displayed. Also, FIG. 11 shows a case where the fluctuation range data calculation unit 220 has determined that the increments are 5° in a range of ±30° with respect to the course obtained as the current observation data of the other ship Sb (a total of 12 fluctuation range data). Here, the first navigation interference zone OZT is displayed in a position aligned in a straight line passing through own ship Sa and the opposing ship Sb, and multiple second navigation interference zones OZTc2a and OZTc2b are also displayed.

[0074] Here, the effectiveness of the avoidance can be evaluated by determining the OZT for the own ship Sa as seen from the other ship Sb. Specifically, it can be evaluated based on the angle of deviation from the course line starting from the other ship Sb to the OZT for the own ship Sa (how much the OZT for the own ship Sa is from the bow of the other ship Sb as seen from the other ship Sb). The angle of deviation can be calculated by determining a navigation interference zone (first navigation interference zone or second navigation interference zone) with the course of the other ship Sb as a specified angle, and aiming the own ship at the edge of the navigation interference zone. Note that at the CPA (Closest Point of Approach), the own ship Sa and the other ship Sb are considered as points, so the CPA is the same value when viewed from either side. Therefore, especially when there is a speed difference between the two ships, the avoidance action area left for the other ship cannot be correctly evaluated.

[0075] In Figure 11, for example, if ship Sa aims for a course that will avoid the tip of the second navigation interference zone OZTc215, which is the case when the course of the other ship Sb changes by -15° within the second navigation interference zone OZTc2b, the OZT for ship Sa as seen from the other ship Sb is obtained as shown in Figure 12. FIG. 12 is a diagram showing OZTc4 relative to the own ship Sa as seen from the other ship Sb in the relationship between the own ship Sa and the other ship Sb shown in FIG. 11. As shown in this figure, OZTc4 is about 15° away from the course of the other ship Sb. In other words, by changing the course of the own ship Sa to avoid the second navigation interference zone OZTc215, the own ship Sa can take avoidance action with plenty of time from an early stage, and for the other ship Sb, the position of the OZT that was visible in front of the other ship Sb changes to a position shifted 15° to the port side as seen from the other ship Sb, so that the OZT is no longer in front of the other ship Sb, and the burden on the other ship Sb can be reduced. In addition, for the other ship Sb, the burden of the collision risk can be reduced from an early stage, so the degree of security is also increased. Therefore, by considering the tip of the second navigation interference zone when the other ship Sb changes course by approximately ±30°, the calculation logic of the engine that calculates the collision can be used as is, and since there is no need to perform complex calculations, the calculations can be simplified and maneuvering can be performed that also takes into account the peace of mind (effect of avoidance) from the other ship Sb's perspective.

[0076] In the above-described embodiment, the output unit 250 is described as displaying both the first navigation interference zone and the second navigation interference zone on the display screen, but it may be configured to display only one of them based on an instruction from the input unit 210.

[0077] In the above-described embodiment, the fluctuation data calculation unit 220 may calculate the fluctuation data according to a predetermined calculation method, or may receive an operation input from the input unit 210 specifying the calculation method and obtain the fluctuation data according to the specified content. For example, the input unit 210 receives a specification of either calculation method A (degree of change based on past behavioral trends) or calculation method B (predetermined range) based on the operation content input by the operator via a touch panel or the like. The fluctuation data calculation unit 220 obtains the fluctuation data according to the calculation method input from the input unit 210 and outputs the obtained fluctuation data to the calculation unit 240. As a result, the OZT is calculated according to the fluctuation data obtained according to the calculation method input from the input unit 210 and is displayed on the display screen. As a result, the operator can switch the OZT to be displayed on the screen according to the situation at that time, such as the type of the other ship, the behavior, and the weather and sea conditions, and grasp the collision risk.

[0078] The fluctuation data may also be a value calculated using a measurement error of the course of the other ship. For example, if the measurement error of a sensor that measures the course is ±3° is described in the sensor's specifications, the input unit 210 acquires the data of the specifications from an external device, and accepts input of data indicating that the measurement error is ±3°, and the fluctuation data calculation unit 220 supplies -3° and 3° as the fluctuation data to the collision calculation unit 241. As a result, the collision calculation unit 241 may determine a first navigation interference zone based on the current measurement result of the COG of the other ship, and may also determine a second navigation interference zone for the course in each case of ±3° from the measurement result of the COG. In this case, two second navigation interference zones are determined. Furthermore, when the measurement error of the SOG is ±5°, by inputting data indicating that the measurement error is ±5% via the input unit 210, the swing width data calculation unit 220 calculates the SOG when it is decreased by 5% from the current SOG and supplies it to the collision calculation unit 241, and also calculates the SOG when it is increased by 5% from the current SOG and supplies it to the collision calculation unit 241. In this way, the collision calculation unit 241 may calculate a first navigation interference zone based on the current SOG measurement result of the other ship, and may also calculate a second navigation interference zone for the course in each case of ±5% from the SOG measurement result. In this case, two second navigation interference zones are calculated.

[0079] Second Embodiment Next, a second embodiment will be described. FIG. 13 is a schematic block diagram showing the configuration of a system in which a navigation support device according to the second embodiment is used. In the second embodiment, the navigation management system 10 and the navigation support device 20A are communicatively connected. In the second embodiment, the same functions as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. In the first embodiment, a case where the first and second navigation interference zones are displayed on the display screen has been described, but in the second embodiment, a function is provided to assist in maneuvering a ship to follow the other ship by using at least one of the first and second navigation interference zones. In the second embodiment, the second navigation interference zone may be displayed on the display screen, but may not be displayed.

[0080] Here, siding refers to a ship maneuvering method in which a ship is steered so as not to cause concern about collision with ships crossing the ship's route. Fig. 14 is a diagram showing an example of a route when a ship is being followed. T0, T1, and T2 each indicate a time, and indicate that time has passed in the order of time T0, time T1, and time T2. When a ship is being followed to a different ship, at time T0, ship Sa0 navigates a route that points to the direction of the different ship Sb0. Next, after ship Sa0 navigates along the route at time T0, ship Sa1 navigates a route that points to the direction of the different ship Sb1 at time T1, and ship Sa2 navigates a route that points to the direction of the different ship Sb2 at time T2. In this way, when a ship is being tacked, it navigates based on a route that points its own ship's course to the direction of the other ship at each time. By navigating the tackling route, the ship can clearly indicate its intention to avoid collision to the other ship that crosses its course, and the anxiety of the other ship's operator about the risk of collision can be reduced. Note that, while the tackling has been described as an example in which the ship's course is pointed toward the other ship, the ship's course does not necessarily need to point toward the other ship as long as the ship can navigate in a way that easily conveys its intention to avoid collision to the other ship.

[0081] In the second embodiment, the calculation unit 240A differs from the first embodiment in that, in addition to the collision calculation unit 241, it further has a first determination unit 242, a second determination unit 243, a third determination unit 244, an angle determination unit 245, a matching relationship determination unit 246, and an angle rank selection unit 247. The first determination unit 242 determines an initial course when the ship takes evasive action against an opposing ship. The second determination unit 243 determines a course to be taken when the ship changes course from the initial course to a different course in order to maneuver around the other ship after the ship has sailed along the initial course. The third determination unit 244 determines the course of the ship after the tracking is completed. The angle determination unit 245 determines the relative magnitude of the angles between the ship's heading when the ship is being tracked and the heading when the ship is terminated. For example, the angle determination unit 245 determines whether the angle of the heading in the direction toward the ship's destination is smaller than the angle of the ship's heading when the ship is being tracked. If the angle determination unit 245 determines that the angle is smaller, the ship can end the track and use the ship's heading as the heading to the destination.

[0082] The meeting relationship determination unit 246 determines the meeting relationship between the ship and the other ship. Figure 15 is a diagram explaining the meeting relationship. Figure 15 is quoted from Figure 1 in the reference (Miyake Rina, Fukudo Junji, Hasegawa Kazuhiko: Application of Automatic Collision Avoidance Maneuvering Function Introduced in a Ship Maneuvering Simulator to Congested Waters, Transactions of the Japan Society of Mechanical Engineers, Series C, Vol. 78, pp. 3408-3412, 2012). The meeting relationship between two ships is classified as one of the meeting relationships based on positional relationship. There are three types of meeting relationships: "meeting" where the two ships, the ship itself and the other ship, approach each other while looking directly at each other, "crossing" where the two ships approach each other while looking sideways, and "overtaking" where one ship approaches from behind and overtakes the other. Furthermore, there are two types of "crossing" and "overtaking": when there is an obligation to avoid collision and when the course is maintained. In the second embodiment, a case will be described in which an avoidance route for the ship itself is generated when there is a matching relationship between "meeting" and "crossing" when there is an obligation to avoid collision.

[0083] When the first determination unit 242 determines an initial course, the angle rank selection unit 247 selects an angle rank (angle rank) based on the distance between the first navigation interference zone and the own ship, which is obtained by performing a collision calculation between the own ship and the other ship. This selected angle can be used as the angle of the initial course (first angle). The angle rank is also referred to as the angle rank. The angle rank is expressed by the angle. For example, the angle rank of an angle of 5° is an angle rank of 5°, and the angle rank of an angle of 30° is an angle rank of 30°. This angle rank can use an angle represented by the amplitude data. That is, if the angle based on the amplitude data is 20°, it can be used as an angle rank of 20°.

[0084] The angle rank selection unit 247 selects an angle rank such that the angle indicated by the angle rank becomes smaller as the distance between the ship and the first navigation interference zone becomes longer. The angle rank selection unit 247 may, for example, store angle rank data in a memory area indicating the relationship between the distance from the ship to the first navigation interference zone and the angle rank, and may select the angle rank by referring to this angle rank data. The angle rank data may be used only when determining the ship's initial course at the start of the stalking action, and does not need to be used after stalking has begun.

[0085] FIG. 16 is a graph showing an example of the angle rank data. The vertical axis indicates the angle rank, and the horizontal axis indicates the distance between the ship and the first navigation interference zone (OZT distance). In this example, the angle rank that the ship should avoid is approximately inversely proportional to the OZT distance. When the distance from the ship to the OZT is long, an angle rank corresponding to a small angle is selected, and the shorter the OZT, the larger the angle rank is selected. When the distance from the ship to the OZT is short, a large angle rank is selected as the angle of the initial course. The angle rank data may be values ​​other than those shown in FIG. 16 depending on the characteristics of the sea area, the degree of congestion, the degree of congestion, etc. of the sea area, as long as the angle indicated by the angle rank becomes smaller as the distance between the ship and the first navigation interference zone becomes longer. In FIG. 16, the angle rank is specified for an OZT distance of up to 6 miles, and the angle rank is 5° when the distance is 6 miles, but in a sea area that is prone to congestion, the angle rank may be specified for up to 3 miles, and the angle rank may be specified to be 5° when the distance is 3 miles. In congested waters, managing collisions up to six miles away can result in a large number of ships being involved, making avoidance difficult. In addition, in Figure 16, the angle rank data is 5° when the OZT distance is 6 miles, but in the case of crossing, different angle rank data may be used depending on the meeting relationship between the own ship and the other ship, such as the angle rank being 10° when the OZT distance is 6 miles.

[0086] Next, the operation of the navigation support device 20A will be described. FIG. 17 is a flowchart illustrating the operation of the navigation support device 20A. The input unit 210 of the navigation support device 20A acquires various data from the navigation management system 10 (step S201). The process of this step S201 is similar to step S101 in the first embodiment. When various data are input to the input unit 210, the calculation unit 240 determines a first navigation interference zone based on the input various data by the collision calculation unit 241 (step S202). The process of this step S202 is similar to step S102 in the first embodiment. Next, the calculation unit 240 determines whether or not a first obstruction zone (OZT) is present within a target range based on the own ship (step S203). The target range is a range of a reference distance based on the own ship. The reference distance may be determined arbitrarily according to the distance over which the other ship can be avoided. For example, it may be determined according to the distance the ship can travel in a reference time. The reference time may be determined, for example, based on the time required to avoid the other ship, for example, 30 minutes. When the speed of the own ship is 12 knots, the distance that can be traveled in 30 minutes is 6 miles. In this case, the reference distance can be set to 6 miles. The reference distance may be changed arbitrarily according to the reference time.

[0087] Next, the calculation unit 240 judges whether or not the first navigation interference zone is present within the target range (step S203). If the first navigation interference zone is not present within the target range (step S203-NO), the calculation unit 240 shifts the process to step S201 after a certain waiting time has elapsed. On the other hand, if the first navigation interference zone is present in the target range (step S203-YES), the calculation unit 240 acquires the distance between the ship and the first navigation interference zone (step S204). In this case, if the target range is set to 6 miles, the distance acquired in step S204 is 6 miles. If the target range is set to 3 miles, the distance acquired in step S204 is 3 miles.

[0088] Next, the collision calculation unit 241 determines a second navigation interference zone based on the fluctuation width data for the other ship that is causing the first navigation interference zone determined to be within the target range in step S203 (step S205). The fluctuation width data may be acquired from the fluctuation width data calculation unit 220, as in the first embodiment. Furthermore, the fluctuation width data may be within a range that can reduce the collision risk even if the course of the other ship fluctuates when performing various route generation processes described below, and can reduce the anxiety of the operator of the other ship about the collision risk. In this example, a case will be described where the fluctuation width data is ±30°.

[0089] Next, the angle rank selection unit 247 selects a first angle based on the distance from the ship to the first navigation interference zone (step S206). Here, when the distance to the first navigation interference zone is 6 miles, the angle rank selection unit 247 selects an angle rank of 5° based on the angle rank data.

[0090] Next, the match relationship determination unit 246 calculates a Line of Predicted Collision (LOPC) based on the trajectory of predicted collision points based on the respective positions, courses, and speeds of the ship and the other ship, and determines the match relationship based on where on the LOPC the first navigation interference zone is located (step S207).

[0091] The LOPC is a display of predicted points of collision (PPC) as a trajectory. The PPC is the intersection of the course of the other ship and the LOPC. The meeting relationship determination unit 246 determines the meeting relationship based on where such a PPC is located on the LOPC. PPC is the speed of the ship V O The speed of the other ship relative to V T The speed ratio K (K=V T / V O ) and also depending on the ship's course and the course of the other ship. The LOPC shows the trajectory of such changes in the PPC.

[0092] 18 is a diagram showing an example of a case where LOPC is calculated, in which the vertical axis (Y axis) corresponds to the north-south direction (up is north), and the horizontal axis (X axis) corresponds to the east-west direction. Here, the position of the own ship O is set as the origin ((X,Y)=(0,0)), and the case where the own ship O and the other ship T are positioned side by side is shown. In addition, the case where the own ship O and the other ship T are considered as "points" without taking into account the size of the hull is shown. In addition, the speed V of the own ship is calculated as follows: Ois 12 knots, the speed of the other ship is V T If the speed is 18 knots, the distance between your ship and the other ship is 3.5 miles, and the bearing Az of the other ship relative to your ship is 90° (here, north is 0°), the LOPC is calculated as a circle surrounding your ship O. This LOPC indicates the position where your ship and the other ship may collide. For example, if the other ship is heading for course CT (Course of Target), the intersections ISa and ISb of the LOPC and course CT indicate the positions where collision is possible. In this case, if your ship sets its course to either ISa or ISb, it indicates that a collision may occur, and if your ship sets its course to a point that is neither ISa nor ISb, it indicates that a collision will not occur.

[0093] In calculating LOPC, the ship's speed is V O , the speed of the opponent ship is V T Then, the speed ratio K is calculated based on the following equation (1). K=V T / V O (1)

[0094] Next, the distance X from the own ship O to the center of the LOPC C is calculated based on the following formula (2). X C =D / (1-K 2 ) · · · (2) Here, D is the distance from own ship O to the other ship T.

[0095] And the X coordinate of the center of the LOPC X is calculated based on the following formula (3). LOPC X =X C sin(Az) (3) Here, Az is the direction of the other ship T as seen from the own ship O when north is 0°.

[0096] Next, the Y coordinate of the center of the LOPC Y is calculated based on the following formula (4). LOPC Y =X Ccos(Az) (4)

[0097] And the radius of the LOPC R is calculated based on the following formula (5). LOPC R =|(K×D) / (1-K 2 )|···(5)

[0098] In this way, the LOPC can be calculated. The LOPC can be calculated regardless of the course of own ship O. In this case, since the speed of own ship O is slower than the speed of the other ship T, the LOPC is calculated as a circle surrounding own ship O. If the speed of own ship O is faster than the speed of the other ship T, the LOPC is calculated as a circle surrounding the other ship T, and if the speeds of own ship O and the other ship T are the same, the LOPC is calculated as a perpendicular bisector.

[0099] The LOPC is disclosed in the following References 1 and 2. Matched relationship determination unit 246 may calculate the LOPC based on the methods described in these references. Moreover, the calculation of the LOPC may be performed by the matched relationship determination unit 246 or by the calculation unit 240.

[0100] 《Reference 1》 Imazu Hayama: Collision prediction lines and collision danger, Japan Institute of Navigation NAVIGATION, No.186, pp.41-44, October 2013 《Reference 2》 Imazu H (2017) Evaluation method of collision risk by using true motion. TransNav Int J Mar Navig Saf Sea Transport 11(1):65-70

[0101] Here, PPC and LOPC are calculated by treating own ship O and target ship T as "points", but when the size of the hulls of own ship O and target ship T is taken into account, PPC is calculated as a "line". This line is the first navigation interference zone. Therefore, the first navigation interference zone exists at a position that passes through the LOPC. Here, because there are intersections ISa and ISb, there are two first navigation interference zones: first navigation interference zone OZTa1 that passes through intersection ISa, and first navigation interference zone OZTa2 that passes through intersection ISb. In addition, regarding the technology that determines the space occupied by the other ship based on the hull shape of the own ship and the hull shape of the other ship, and calculates the collision course and the time of closest approach based on the speed of the own ship and the other ship, the course of the other ship, the direction of the other ship, and the distance to the other ship, thereby showing the interference zone, which indicates the area where there is a risk of collision with the other ship, with a line segment, the technology may be used, for example, as described in Reference 3 below.

[0102] 《Reference 3》 JP 2021-187422 A

[0103] The shape of the LOPC is determined according to the speed of the ship and the other ship. Figures 19 to 21 show examples of LOPC. (1) The speed of your ship and the other ship are the same (V O =V T , i.e., K = 1), the LOPC is indicated by the perpendicular bisector (Figure 18; LOPCa). (2) Own ship's speed V O The other ship V T Faster than (V O >V T ), the LOPC is indicated by a circle surrounding the other ship (Figure 19; LOPCb). (3) Own ship's speed V O The other ship V T slower than (V O <V T ), the LOPC is indicated by a circle surrounding the ship (Figure 20; LOPCc).

[0104] The meeting relationship determination unit 246 can determine the meeting relationship using the LOPC obtained in this manner. Here, a meeting occurs when the course of the ship heads toward the first navigation interference zone that intersects with the LOPC. Therefore, the meeting relationship determination unit 246 determines the meeting relationship with the other ship when the course of the ship heads toward the first navigation interference zone.

[0105] For example, as shown in Fig. 19, when the speeds of the own ship and the other ship are the same and the LOPC is calculated as a perpendicular bisector, the meeting relationship determination unit 246 assigns three sections to the LOPC and determines which section the course of the other ship will pass through, thereby determining the meeting relationship. Here, the LOPCa is assigned in advance as section HO, a section different from section HO that is in the direction of 0° as seen from the own ship, section CG, and a section different from section HO that is in the direction of 180° as seen from the own ship, as section CS. Then, the meeting relationship determination unit 246 determines that the meeting relationship is crossing (obligation to give way) when the course of the other ship passes through section CG, that the meeting relationship is meeting when the course of the other ship passes through section HO, and that the meeting relationship is crossing (maintaining to give way) when the course of the other ship passes through section CS.

[0106] 20, when the speed of the ship is faster than the speed of the other ship and the LOPC is calculated as a circle surrounding the other ship, the match relationship determination unit 246 assigns four sections to the LOPC and determines which section the course of the other ship will pass through, thereby determining the match relationship. Here, the section of the LOPCb that intersects with the line connecting the ship and the other ship is assigned in advance as section HO, the section different from section HO that is within +112.5° from the line connecting the ship and the other ship is assigned in advance as section CG, the section different from section HO that is within -112.5° from the line connecting the ship and the other ship is assigned in advance as section CS, and the remaining sections are assigned in advance as section OT. The meeting relationship determination unit 246 then determines that the meeting relationship is crossing (obligation to give way) when the course of the other ship passes through section CG, that the meeting relationship is meeting when the course of the other ship passes through section HO, that the meeting relationship is crossing (maintaining to give way) when the course of the other ship passes through section CS, and that the meeting relationship is overtaking when the course of the other ship passes through section OT. Here, when the other ship heads for course COb, course CTb passes through section CG, so it can be determined that the meeting relationship is crossing (obligation to give way).

[0107] 21, when the speed of the ship is slower than that of the other ship and the LOPC is calculated as a circle surrounding the ship, the match relationship determination unit 246 assigns four sections to the LOPC and determines which section the course of the other ship will pass through, thereby determining the match relationship. Here, the section of the LOPCc that intersects with the line connecting the ship and the other ship is assigned in advance as section HO, the section different from section HO that is within +112.5° from the line connecting the ship and the other ship is assigned in advance as section CG, the section different from section HO that is within -112.5° from the line connecting the ship and the other ship is assigned in advance as section CS, and the remaining sections are assigned in advance as section ON. The meeting relationship determination unit 246 then determines that the meeting relationship is crossing (obligation to give way) when the course of the other ship passes through section CG, that the meeting relationship is meeting when the course of the other ship passes through section HO, that the meeting relationship is crossing (maintaining to give way) when the course of the other ship passes through section CS, and that the meeting relationship is to be overtaken when the course of the other ship passes through section ON. Here, when the other ship heads for course COc, course CTc passes through section CG, so it can be determined that the meeting relationship is crossing (obligation to give way).

[0108] The range of the above-mentioned interval HO is determined in advance.

[0109] In addition, the meeting relationship determination unit 246 may further determine a section Ex-HOa between the section HO and the section CG, and a section Ex-HOb between the section HO and the section CS. Here, as described later, for the section near the boundary between the section HO and the section CG, and the section near the boundary between the section HO and the section CS, the ship is basically a crossing ship, so it is sufficient to implement an approach or irregular approach, but depending on the relationship between the ship and the other ship and the conditions of the sea area, there is a possibility that the passing distance between the ship and the other ship cannot be secured. Therefore, the sections Ex-HOa and Ex-HOb may be set in the sections near these boundaries. It can be said that the other ship is in a relationship between meeting and crossing with respect to the ship in these sections Ex-HOa and Ex-HOb.

[0110] Figures 22 to 24 are diagrams explaining crossing ships whose match-up relationship is close to that of a meeting ship. For example, when the speeds of the own ship and the other ship are the same and the LOPC is calculated as a perpendicular bisector as shown in Figure 22, the meeting relationship determination unit 246 assigns five sections to the LOPC and determines which section the other ship's course passes through, thereby determining the meeting relationship. Here, a section Ex-HOa is provided between sections HO and CG, and a section Ex-HOb is provided between sections HO and CS. If the other ship's course passes through the section Ex-HOa or the section Ex-HOb, the meeting relationship determination unit 246 determines that the meeting relationship is a "crossing ship close to a meeting ship" (the other ship is in a relationship between meeting and crossing with respect to the own ship).

[0111] Furthermore, as shown in Figure 23, when the speed of the own ship is faster than the speed of the other ship and the LOPC is calculated as a circle surrounding the other ship, the meeting relationship determination unit 246 assigns six sections to the LOPC and determines which section the other ship's course passes through, thereby determining the meeting relationship. Here, section Ex-HOa is provided between section HO and section CG, and section Ex-HOb is provided between section HO and section CS. Then, when the other ship's course passes through section Ex-HOa or section Ex-HOb, the meeting relationship determination unit 246 determines that the meeting relationship is a "crossing ship close to a meeting ship" (the other ship is in a relationship between meeting and crossing with respect to the own ship).

[0112] Furthermore, as shown in Figure 24, when the speed of the own ship is slower than the speed of the other ship and the LOPC is calculated as a circle surrounding the own ship, the meeting relationship determination unit 246 assigns six sections to the LOPC and determines which section the other ship's course passes through, thereby determining the meeting relationship. Here, section Ex-HOa is provided between section HO and section CG, and section Ex-HOb is provided between section HO and section CS. Then, when the other ship's course passes through section Ex-HOa or section Ex-HOb, the meeting relationship determination unit 246 determines that the meeting relationship is a "crossing ship close to a meeting ship" (the other ship is in a relationship between meeting and crossing with respect to the own ship).

[0113] Here, the range of the sections Ex-HOa and Ex-HOb may be within a range of ±15° based on a straight line connecting the ship and the other ship. This angle is not limited to ±15° and may be an angle other than ±15°. By providing such sections Ex-HOa and Ex-HOb and generating a route for an encounter (described later), it becomes easier to ensure the passing distance between the ship and the other ship, and it becomes easier to inform the helmsman of the other ship of the ship's intention to take evasive action, thereby reducing the helmsman of the other ship's anxiety about the risk of collision.

[0114] When the meeting relationship is determined, the calculation unit 240 performs a route generation process according to the meeting relationship. Here, when the determination result of step S207 is that the meeting relationship is a meeting vessel or a crossing vessel close to a meeting vessel (the other vessel is in a relationship between meeting and crossing with respect to the own vessel), the calculation unit 240 performs a route generation process for the meeting (step S208). On the other hand, if the result of the judgment in step S207 is that the meeting relationship is that of a crossing ship (obligation to give way), the calculation unit 240 determines whether the course to avoid the second navigation interference zone corresponding to the angle rank is greater than the bearing of the other ship (step S209), and if the course to avoid the second navigation interference zone corresponding to the angle rank is greater than the bearing of the other ship (step 209-YES), it performs route generation processing by following (step S210), and if the course to avoid the second navigation interference zone corresponding to the angle rank is equal to or less than the bearing of the other ship (step 209-NO), it performs route generation processing by irregular following (step S211). Here, the course that avoids the second interference zone corresponding to the angle rank is a course that avoids the second interference zone corresponding to an angle rank (angle rank) selected based on the distance between the first interference zone and the own ship, which is calculated by performing a collision calculation between the own ship and the other ship, among the second interference zones (the interference zones calculated based on the swing data) that occur when the other ship's course changes course by a first angle. For example, if the angle rank corresponding to the distance to the first interference zone is obtained as 20° (angle rank 20°) based on the angle rank data, the course that avoids the second interference zone corresponding to 20° among the second interference zones (for example, a plurality of second interference zones within a range of ±30° from the first interference zone).

[0115] Here, in step S207, if the meeting relationship is determined to be a crossing ship (maintaining to give way) or an overtaken ship, the calculation unit 240 generates a route to maintain the course without taking any avoiding action. Also, if the meeting relationship is determined to be a crossing ship (maintaining to give way) or an overtaken ship, the calculation unit 240 generates a route to maintain the course without taking any avoiding action. In this case, the obligation to give way lies with the other ship, so a collision is avoided by the other ship taking avoiding action. Although the above-described embodiment does not refer to the route generation process for overtaking, the route generation process for meeting may be applied to overtaking as well.

[0116] Next, the route generation process for an encounter, the route generation process for following, and the route generation process for irregular following will be described.

[0117] Route generation process for meetings FIG. 25 is a flowchart illustrating the route generation process for a meeting. In route generation processing for encounters, when the course of the ship is in a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the ship and the other ship, and the other ship is in an encounter relationship with the ship, the first determination unit 242 determines, as the course of the ship, a first course that is a course that can avoid a second navigation interference zone that occurs when the course of the other ship changes course at a first angle (step S301). Here, the first course is a course that can avoid a second navigation interference zone according to an angle rank. For example, when the angle rank is 15°, the first course is a course that can avoid a second navigation interference zone corresponding to an angle rank of 15°.

[0118] Fig. 26 is a diagram for explaining the process in which the first determination unit 242 determines a course in relation to a crossing ship close to an encounter ship. The diagram shown in Fig. 26 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, at time t1, own ship O and other ship T are in a meeting relationship, and a first navigation interference zone OZT1 exists, which indicates an area where a collision risk occurs, as determined by a collision calculation. Then, own ship O's course COa was heading toward the destination, but since it is detected that it is heading toward this first navigation interference zone OZT1, it becomes necessary to take avoiding action. When the other ship T is in a meeting relationship with the first ship O, the first course CO1, which is a course that can avoid the second navigation interference zone OZT2 that occurs when the course of the other ship T changes course at the first angle θ1, is determined as the course of the first ship. Here, the first angle θ1 is determined as the angle θ Rank15 (for example, 15°). In this way, by heading the ship's course toward the second navigation interference zone OZT2, if the other ship T navigates without changing its course, the ship can avoid the first navigation interference zone OZT1, and even if the other ship T changes its course within a range less than the first angle θ1, it is possible to avoid the risk of collision, so that the ship can take avoidance action with ample time to maneuver. In addition, the ship O can clearly indicate its intention to avoid collision, giving the operator of the other ship T peace of mind regarding the risk of collision.

[0119] Next, the calculation unit 240 generates a route for traveling in the course determined in step S301 until the second navigation interference zone with an angle rank of 30° is reached on the course of the ship (step S302). 27 is a diagram showing the relationship between the own ship O and the other ship T at time t2, which is a certain time after the processing of step S301. The diagram shown in FIG. 27 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, own ship O is angled at θ Rank15 The diagram shows the case where ship O continues sailing on a course toward the target, and the other ship T maintains its course. Rank15 As the ship O navigates on a course toward the first navigation interference zone OZT1, the distance from the ship O to the second navigation interference zone also becomes shorter as the distance between the ship O and the other ship T becomes shorter. Therefore, the course of the ship O was heading toward the second navigation interference zone OZT with an angle rank of 15° at time t1, but if the ship O navigates on its own course, the second navigation interference zone OZT22 will be present on the ship O's course at time t2. Here, the second navigation interference zone OZT22 has an angle rank of 25°. Therefore, even if the course of the other ship T is changed within a range of less than 25°, it is possible to avoid the risk of collision, and the ship O can navigate with a greater degree of leeway as time passes. This makes it possible to clearly indicate the ship O's intention to avoid collision, and to give the operator of the other ship T peace of mind regarding the risk of collision.

[0120] Next, when the second determination unit 243 detects that the ship has navigated based on the first course until it reaches a third navigation interference zone (e.g., angle rank 30°) that occurs when the course of the other ship changes course at a second angle greater than the first angle, it determines the ship's course as the second course, which is a course toward the third navigation interference zone (step S303). 28 is a diagram showing the relationship between the own ship O and the other ship T at time t3, which is a certain time after the processing of step S302. The diagram shown in FIG. 28 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, own ship O is angled at θ Rank15 The diagram shows the case where ship O continues sailing on a course toward the target, and the other ship T maintains its course. Rank15 As the ship O navigates along its course toward the first navigation interference zone OZT1, and the distance between the ship O and the other ship T becomes closer, the distance from the ship O to the first navigation interference zone OZT1 also becomes closer, and the distance to the second navigation interference zone also becomes closer. Therefore, the course of the ship O was heading toward the second navigation interference zone OZT with an angle rank of 15° at time t1, but if the ship O continues to navigate along its course, the second navigation interference zone OZT23 will be present on the ship O's course at time t3. Here, the second navigation interference zone OZT23 has an angle rank of 30°. When the second determination unit 243 detects that the second navigation interference zone OZT23 with an angle rank of 30° has arrived on the first course CO1, it determines the course of the ship O as the second course, which is a course toward the second navigation interference zone OZT23. Here, since the second course is the second navigation interference zone OZT23, as the ship O and the other ship T get closer, the position of the second navigation interference zone OZT23 also gets closer, but the second determination unit 243 determines the course to follow this second navigation interference zone OZT23. As a result, a route that follows the second navigation interference zone OZT23 is generated. Here, even if the course of the other ship T is changed by less than 30 degrees, it is possible to avoid the risk of collision and take evasive action while maintaining a degree of leeway. In addition, it is possible to clearly indicate that own ship O is continuing to take evasive action, giving the navigator of the other ship T peace of mind regarding the risk of collision.

[0121] Next, the calculation unit 240 generates a route for traveling in the direction of the ship's own course so that the ship travels toward the second course, which is a course heading toward the third navigation interference zone (angle rank 30°), for a certain period of time (step S304). The certain period of time is, for example, 5 minutes, and if the ship O's speed is 12 knots, the ship travels 1 mile after traveling for the certain period of time.

[0122] After sailing along the route in step S304 for a certain period of time, the angle determining unit 245 determines which is larger between the angle toward the second course and the course-changing angle when the ship changes course to its destination (step S305). Based on the judgment result of the angle judgment unit 245, when it is judged that the course-changing angle when changing course toward the ship's destination is smaller than the angle toward the second course (step S305-YES), the third determination unit 244 determines the ship's course to be the third course, which is the course in a direction toward the destination (step S306).

[0123] 29 is a diagram showing the relationship between the own ship O and the other ship T at time t4, which is a certain time after the processing of step S304. The diagram shown in FIG. 29 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, the diagram shows a case where the own ship O continues to navigate on a course heading into the second navigation interference zone OZT23 with an angle rank of 30°, while the other ship T maintains its course. As the own ship O navigates on a course heading into the second navigation interference zone OZT23 and the distance between the own ship O and the other ship T becomes closer, the own ship O's course change angle gradually increases. As the own ship O continues to change course, it reaches an angle at which its course points toward the destination. If the own ship O then further navigates on a course heading into the second navigation interference zone OZT23, its course will point away from the angle at which it points toward the destination. In this case, the angle θ toward the second course Rank30 The course change angle θ when the ship changes course to its destination D is smaller. Therefore, when the angle determination unit 245 determines the magnitude relationship between the angle toward the second course and the course-changing angle when the ship changes course toward the ship's destination, and it determines that the course-changing angle when the ship changes course toward the ship's destination is smaller than the angle toward the second course, it detects that the course-changing angle will be smaller if the ship's course is directed toward the destination rather than the second navigation interference zone OZT23. As a result, the course CO3 of the ship O is set to the heading toward the destination.

[0124] On the other hand, if the course-changing angle when changing course toward the ship's destination is not smaller than the angle toward the second course (if the course-changing angle when changing course toward the ship's destination is greater than or equal to the angle toward the second course), the calculation unit 240 transitions to step S303.

[0125] When performing the route generation process for the encounter described above, a course that avoids the second interference zone corresponding to the angle rank determined according to the distance to the first interference zone (OZT) is selected as the initial course of the ship, and a route is generated so that the initial course of the ship follows the second interference zone of the other ship at the timing when the initial course of the ship avoids the second interference zone of the other ship corresponding to the angle rank of 30°. When the encounter is a encounter, the initial course of the ship is maintained until the course of the ship avoids the second interference zone corresponding to the angle rank of 30°, and then the second interference zone corresponding to the angle rank of 30° is followed, thereby reducing the anxiety of the operator of the other ship regarding the collision risk. In addition, when the second interference zone corresponding to the angle rank of 30° is followed, it means that there will be no collision even if the other ship changes course by 30°, so that the operator of the other ship can be given sufficient peace of mind. Note that, although the case of following the second navigation interference zone corresponding to an angle rank of 30° has been described here, other angles may be used as long as they are greater than the angle of the angle rank determined in the ship's initial course and are within the angle rank of 30°, as long as it is possible to reassure the operator of the other ship. Note that the course is set to return the ship's course to the destination direction at the timing shown in Figure 29 (when the angle determination unit 245 determines the magnitude relationship between the angle toward the second course and the course change angle when changing course toward the ship's destination, and determines that the course change angle when changing course toward the ship's destination is smaller than the angle toward the second course), but rather than immediately returning to the destination direction at this timing, the ship may return to the original course (the course before the ship took CO1, i.e., 0°, the course before taking evasive action).Then, after sailing along the current course for a certain period of time, the ship's course may be set to the destination direction.

[0126] <Route generation process by tracking> 30 is a flowchart for explaining the route generation process by following. Following is a process executed in the case of a crossing ship (obligation to give way). In the route generation process by following, when the ship's heading is in a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the ship and the other ship, the other ship is in a crossing relationship with the ship, and the heading that avoids the second navigation interference zone corresponding to the angle rank is greater than the bearing of the other ship, the first determination unit 242 determines the ship's heading to be the fourth course, which is a course toward the other ship (step S401). Fig. 31 is a diagram for explaining the process in which the first determination unit 242 determines a course in relation to a crossing ship (obligation to give way). The diagram shown in Fig. 31 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, at time t1, own ship O and other ship T are in a crossing relationship, and a first navigation interference zone OZT1 exists, which indicates an area where a collision risk occurs, as determined by a collision calculation. Then, own ship O's course COa was heading toward the destination, but since it is detected that it is heading toward this first navigation interference zone OZT1, it becomes necessary to take avoiding action. Then, when the opposing ship T is in a crossing relationship with the first ship O (obligation to give way), and the course that avoids the second navigation interference zone corresponding to the angle rank is greater than the bearing of the opposing ship, the fourth course COb, which is a course heading toward the opposing ship T, is determined as the course of the first ship O (step S401). As a result, the course COb of the first ship O is oriented to avoid the first navigation interference zone OZT1, and avoidance action can be taken. In addition, by turning the course of the first ship O toward the opposing ship T, the course COb of the first ship O now faces a bearing that allows it to avoid the second navigation interference zone OZT2. This second navigation interference zone OZT2 corresponds to an angle rank of 15°, so even if the course of the opposing ship T is changed within a range of less than 15°, it is possible to avoid the risk of collision, and avoidance action can be taken with plenty of time to spare. Furthermore, with this maneuver, even if ship O's course is set to face other ship T, it is easy to communicate to the navigator of the other ship that ship O's course is not pointing to any position on the course of other ship T. Therefore, even if ship O's course is set to face other ship T, the burden felt by the navigator of other ship T is small. This makes it possible to clearly indicate ship O's intention to avoid collision, and to give the navigator of other ship T peace of mind regarding the risk of collision.

[0127] Next, the calculation unit 240 generates a route for traveling in the direction of the ship's own course so that the ship O travels for a certain period of time toward the fourth course, which is a course heading toward the other ship T (step S402). The certain period of time here is, for example, 5 minutes, and if the ship O's speed is 12 knots, the ship will travel 1 mile after traveling for the certain period of time.

[0128] 32 is a diagram showing the relationship between the own ship O and the other ship T at time t2, which is a certain time after the processing of step S401. The diagram shown in FIG. 32 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, the case is illustrated where the ship O continues sailing on a course toward the other ship T, and the other ship T maintains its course. As the ship O sails on a course toward the other ship T and the distance between the ship O and the other ship T becomes closer, the ship O's course change angle gradually becomes smaller. At time t1, the course COb of the ship O includes a second navigation interference zone OZT2, but at time t2, the course COb of the ship O includes a second navigation interference zone OZT22. The second navigation interference zone OZT2 corresponds to an angle rank of 20°, and the second navigation interference zone OZT22 corresponds to an angle rank of 25°. Therefore, even if the course of the other ship T is changed within a range of less than 25°, it is possible to avoid the risk of collision. In addition, the ship's course gradually approaches a direction toward the destination as time passes. In this way, by following behind, ship O can take evasive action with plenty of time to spare, clearly indicating ship O's intention to avoid collision, and giving the pilot of the other ship T peace of mind regarding the risk of collision.

[0129] Next, the angle determination unit 245 determines which is larger between the angle toward the fourth course and the course-changing angle when the ship changes course toward its destination (step S403). Based on the result of the determination by the angle determination unit 245, if the course change angle is smaller than the angle toward the fourth course (step S403-YES), the third determination unit 244 determines the course of the ship O as the fifth course, which is a course in a direction toward the destination (step S404). Here, the determination of the magnitude relationship performed by the angle determination unit 245 (step S403) may be to determine whether the destination has become lined up on a straight line connecting the ship O and the other ship T. Then, the angle determination unit 245 may maintain the angle toward the fourth course if the destination has not yet become lined up on the straight line connecting the ship O and the other ship T, and may determine the course of the ship O as the fifth course, which is a course in a direction toward the destination, if the destination has become lined up on the straight line connecting the ship O and the other ship T. The angle determination unit 245 may determine whether the angle is greater or smaller (step S403) by determining whether the fourth course has reached the direction toward the destination. If the fourth course has not reached the direction toward the destination, the angle determination unit 245 may maintain the angle toward the fourth course, and if the fourth course has reached the direction toward the destination, the angle determination unit 245 may determine the course of the ship O to be the fifth course, which is the course toward the destination.

[0130] 33 is a diagram showing the relationship between the own ship O and the other ship T at time t3, which is a certain time after the processing of step S402. The diagram shown in FIG. 33 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, the diagram shows a case where the own ship O continues sailing on a course toward the other ship T, and the other ship T maintains its course. As the own ship O sails on a course toward the other ship T and the distance between the own ship O and the other ship T becomes closer, the course change angle of the own ship O gradually increases. As the own ship O continues to change course, it reaches an angle at which its course points toward the destination (the destination is lined up on a straight line connecting the own ship O and the other ship T). If the own ship O then continues sailing on a course toward the other ship T, its course will point away from the angle at which the own ship O's course points toward the destination. In this case, the course change angle when the own ship changes course toward its destination is smaller than the angle toward the other ship T. Therefore, when the angle determination unit 245 determines whether the angle toward the fourth course is larger than the course change angle when the ship changes course toward its destination, it detects that the course change angle will be smaller if the ship O's course is directed toward the destination rather than the target ship T. This ends the process of following the target ship T, and the ship O's course is set to the heading toward the destination (course COc). If the destination direction is smaller than the target ship's heading than the ship's own turning course angle, there is no risk of collision even if the ship's heading is turned to the destination, so avoidance actions for the target ship T can be ended. In other words, it can be said that the target ship T has passed between the ship O and the destination, so avoidance actions for the target ship T can be ended.

[0131] On the other hand, if the course-changing angle when changing course toward the ship's destination is not smaller than the angle toward the fourth course (if the course-changing angle when changing course toward the ship's destination is greater than or equal to the angle toward the fourth course), the calculation unit 240 transitions to step S401.

[0132] When performing the route generation process (management) for a crossing ship (obligation to give way) as described above, the other ship's bearing is selected as the ship's initial course, and the timing for starting maneuvering is immediately in response to the start of the avoidance action, and maneuvering is performed with the bearing of the other ship as the target. When the meeting relationship is a crossing ship (obligation to give way), even if the ship's course is set to face the other ship, it is easy for the helmsman of the other ship to know that the ship's course is not directed to any position on the other ship's course, so even if the course of ship O is set to face the other ship T, the burden felt by the helmsman of the other ship T is small. This makes it possible to reduce the anxiety of the helmsman of the other ship regarding the risk of collision, even if maneuvering is performed with the other ship's bearing as the target. Note that the course is set to return the ship's course to the destination direction at the timing shown in Figure 33 (when the angle determination unit 245 determines the magnitude relationship between the angle toward the fourth course and the course change angle when changing course toward the ship's destination, and determines that the course change angle when changing course toward the ship's destination is smaller than the angle toward the fourth course), but rather than immediately returning to the destination direction at this timing, the ship may return to the original course (the course before the ship took CO1, i.e., 0°, the course before taking evasive action).Then, after sailing along the current course for a certain period of time, the ship's course may be set to the destination direction.

[0133] <<Route generation process using irregular tracking>> FIG. 34 is a flowchart illustrating a route generation process for irregular tracking. In route generation processing using irregular maneuvering, when the ship's heading is in a first navigation interference zone indicating an area where a risk of collision occurs, which is obtained by performing a collision calculation between the ship and the other ship, the other ship is in a crossing position relative to the ship (obligation to give way), and the heading that avoids the second navigation interference zone corresponding to the angle rank is smaller than the bearing of the other ship, the first determination unit 242 determines, as the ship's heading, the first course (at an angle corresponding to the angle rank) that is an avoidable heading for the second navigation interference zone that occurs when the other ship's heading changes course by a first angle (step S501).

[0134] Fig. 35 is a diagram for explaining the process in which the first determination unit 242 determines a course in relation to a crossing ship (obligation to give way). The diagram shown in Fig. 35 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, at time t1, own ship 0 and other ship T are in a crossing relationship close to meeting ships, and a first navigation interference zone OZT1 exists, which indicates an area where a collision risk occurs, as determined by a collision calculation. Then, own ship O's course COa was heading toward the destination, but since it is detected that it is heading toward this first navigation interference zone OZT1, it becomes necessary to take avoiding action. When the other ship T crosses the first ship O (obligation to give way), the first course CO1, which is an avoidable course for the second navigation interference zone OZT2 that occurs when the other ship T changes course at the first angle θ1, is determined as the course of the first ship. Here, the first angle θ1 is the angle θ according to the angle rank determined in step S501. Rank20 (for example, 20°). In this way, by heading the ship's course toward the second navigation interference zone OZT2, if the other ship T navigates without changing its course, the ship can avoid the first navigation interference zone OZT1, and even if the other ship T changes its course within a range less than the first angle θ1, it is possible to avoid the risk of collision, so that the ship can take avoidance action with ample time to maneuver. In addition, the ship O can clearly indicate its intention to avoid collision, giving the operator of the other ship T peace of mind regarding the risk of collision.

[0135] Next, the calculation unit 240 generates a route for traveling in the course direction of the own ship determined in step S501 until the other ship arrives on the course of the own ship (step S502). 36 is a diagram showing the relationship between the own ship O and the other ship T at time t2, which is a certain time after the processing of step S501. The diagram shown in FIG. 36 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, own ship O is angled at θ Rank20 In the figure, the vessel continues to sail toward the course CO1, and the other vessel T maintains the course. Also, at time t2, the other vessel T has not yet arrived at the course CO1. As the ship O navigates along a course CO1 and the distance between the ship O and the other ship T becomes closer, at time t1 a second navigation interference zone OZT2 exists on the course CO1 of the ship O, but at time t2 a second navigation interference zone OZT23 exists on the course COb of the ship O. The second navigation interference zone OZT2 corresponds to an angle rank of 20°, and the second navigation interference zone OZT23 corresponds to an angle rank of 30°, so that even if the course of the other ship T is changed within a range of less than 30°, it is possible to avoid the risk of collision. In this way, by taking avoiding action, ship O can take avoiding action with ample time to spare, clearly indicating the intention of ship O to avoid collision, and giving the pilot of the other ship T peace of mind regarding the risk of collision.

[0136] The second determination unit 243 causes the ship to navigate based on the first course until the other ship reaches the first course, and when the other ship reaches the first course, determines the ship's course to be the sixth course, which is a course toward the other ship (step S503). 37 is a diagram showing the relationship between the own ship O and the other ship T at time t3, which is a certain time after the processing of step S502. The diagram shown in FIG. 37 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, own ship O is angled at θ Rank20 The diagram shows the case where ship O continues sailing on a course toward the target, and the other ship T maintains its course. Rank20 As ship O navigates along a course toward the other ship T, and as the distance between ship O and the other ship T becomes closer, the other ship T reaches course CO1. Based on this, ship O's course is determined as course CO2 toward the other ship T. As a result, as ship O and the other ship T become closer, ship O's course follows the position of the other ship T, and the course change angle of ship O gradually becomes smaller. Here, the course CO2 of the own ship O is not heading toward any of the first navigation interference zone OZT1, the second navigation interference zone OZT2, and the second navigation interference zone OZT23, so even if the course of the other ship T is changed within a range of about 30°, it is possible to avoid the risk of collision and take evasive action while maintaining a degree of leeway. In addition, it is possible to clearly indicate that the own ship O is continuing to take evasive action, giving the navigator of the other ship T peace of mind regarding the risk of collision.

[0137] Next, the calculation unit 240 generates a route for traveling in the direction of the ship's own course so that the ship travels toward the sixth course, which is a course heading toward the other ship, for a certain period of time (step S504). The certain period of time is, for example, 5 minutes, and if the ship O's speed is 12 knots, the ship will travel 1 mile after traveling for the certain period of time.

[0138] After sailing along the route in step S504 for a certain period of time, the angle determining unit 245 determines which is larger between the angle toward the sixth course and the course-changing angle when the ship changes course to its destination (step S505). Based on the judgment result of the angle judgment unit 245, when it is judged that the course change angle is smaller than the angle toward the sixth course (step S505-YES), the third determination unit 244 determines the course of the ship O as the seventh course, which is a course in a direction toward the destination (step S506). Here, the judgment of the magnitude relationship performed by the angle judgment unit 245 (step S505) may be to judge whether the destination has become lined up on a straight line connecting the ship O and the other ship T. Then, the angle judgment unit 245 may maintain the angle toward the sixth course if the destination has not yet become lined up on the straight line connecting the ship O and the other ship T, and may determine the course of the ship O as the seventh course, which is a course in a direction toward the destination, if the destination has become lined up on the straight line connecting the ship O and the other ship T. The magnitude relationship determination performed by the angle determination unit 245 (step S505) may be a determination of whether or not the sixth course has reached the direction toward the destination. If the sixth course has not reached the direction toward the destination, the angle determination unit 245 may maintain the angle toward the sixth course, and if the sixth course has reached the direction toward the destination, the angle determination unit 245 may determine the course of the own ship O as the seventh course, which is the course toward the destination.

[0139] 38 is a diagram showing the relationship between the own ship O and the other ship T at time t4, which is a certain time after the processing of step S503. The diagram shown in FIG. 38 can also be displayed on a display device by the output unit 250 as a calculation result by the calculation unit 240. Here, the diagram shows a case where the own ship O continues sailing on a course toward the other ship T, and the other ship T maintains its course. As the own ship O sails on a course toward the other ship T and the distance between the own ship O and the other ship T becomes closer, the course change angle of the own ship O gradually increases. As the own ship O continues to change course, it reaches an angle at which its course points toward the destination (the destination is lined up on a straight line connecting the own ship O and the other ship T). If the own ship O then further sails on a course toward the other ship T, its course will point away from the angle at which the own ship O's course points toward the destination. In this case, the course change angle when the own ship changes course toward its destination is smaller than the angle toward the other ship T. Therefore, when the angle determination unit 245 determines whether the angle toward the sixth course is larger than the course change angle when the ship changes course toward the ship's destination, it detects that the course change angle will be smaller if the ship's course is set toward the destination rather than the other ship T. This ends the process of following the other ship T, and sets the ship's course to a heading toward the destination (course COc). Here, since the other ship T can be said to have passed between the ship and the destination and the ship's destination, the avoidance action for the other ship T can be ended, and the ship can be set to a course toward the destination.

[0140] On the other hand, if the course-changing angle when changing course toward the ship's destination is not smaller than the angle toward the sixth course (if the course-changing angle when changing course toward the ship's destination is greater than or equal to the angle toward the sixth course), the calculation unit 240 transitions to step S503.

[0141] When performing the above-described irregular route generation process, a course that avoids the second obstruction zone corresponding to the angle rank determined according to the distance to the first obstruction zone (OZT) is selected as the initial course of the ship, and the timing to start the route is when the other ship arrives on the initial course of the ship, and the other ship is followed. Here, since the course change angle of the ship will be large if the ship follows the other ship, the ship maintains its initial course until the course of the ship becomes the other ship's heading, and then the ship follows the other ship's heading. This reduces the anxiety of the other ship's operator about the risk of collision, even if the ship follows the other ship's heading. Note that the course is set to return the ship's course to the destination direction at the timing shown in Figure 38 (when the angle determination unit 245 determines the magnitude relationship between the angle toward the sixth course and the course change angle when changing course toward the ship's destination, and determines that the course change angle when changing course toward the ship's destination is smaller than the angle toward the sixth course), but rather than immediately returning to the destination direction at this timing, the ship may return to the original course (the course before the ship took CO1, i.e., 0°, which is the course before taking evasive action).Then, after sailing along the current course for a certain period of time, the ship's course may be set to the destination direction.

[0142] The navigation support device 20 in the above-mentioned embodiment may be realized by a computer. In that case, a program for realizing the function may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read into a computer system and executed to realize the function. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The term "computer-readable recording medium" may also include a medium that dynamically holds a program for a short period of time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, and a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or client in that case. The above-mentioned program may be a program for realizing a part of the above-mentioned function, or may be a program that can realize the above-mentioned function in combination with a program already recorded in the computer system, or may be a program that is realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0143] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Explanation of symbols]

[0144] 10: navigation management system, 20: navigation support device, 210: input section, 220: width data calculation section, 230: width data supply section, 231: collision calculation section, 240: calculation section, 241: collision calculation section, 250: output section, 260: storage section

Claims

1. a first determination unit that determines, as the course of the first ship, a first course that is an avoidable course for a second interference zone that occurs when the course of the other ship changes course by a first angle, when the course of the first ship is in a first interference zone that indicates an area where a collision risk occurs and is obtained by performing a collision calculation between the first ship and the other ship, and when the other ship is in a meeting relationship with the first ship or in a relationship between meeting and crossing with the first ship; a second determination unit that, when the ship navigates based on the first course until the ship reaches a third navigation interference zone that occurs when the course of the other ship changes course on the first course by a second angle that is larger than the first angle, determines the course of the ship as a second course that is a course toward the third navigation interference zone; an angle determination unit that determines which is larger between an angle toward the second course and a course-changing angle when the ship changes course to its destination; a third determination unit that determines the course of the ship as a third course, which is a course heading toward the destination, when the course change angle is smaller than the angle toward the second course; A navigation aid having:

2. a first determination unit that determines a fourth course, which is a course heading toward the other ship, as the course of the own ship when the course of the own ship is in a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the own ship and the other ship, the other ship is in a crossing relationship with the own ship, and a course that avoids a second navigation interference zone corresponding to an angle rank is greater than the bearing of the other ship; and an angle determination unit that determines which is larger between an angle toward the fourth course and a course-changing angle when the ship changes course to its destination; a third determination unit that determines the course of the ship as a fifth course, which is a course heading toward the destination, when the course change angle is smaller than the angle toward the fourth course; A navigation aid having the following:

3. a first determination unit that, when the course of the first ship is in a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the first ship and the other ship, the other ship is in a crossing relationship with the first ship, and a course that avoids a second navigation interference zone corresponding to an angle rank is equal to or less than the bearing of the other ship, determines, as the course of the first ship, a first course that is an avoidable course for the second navigation interference zone that occurs when the course of the other ship changes course by a first angle; a second determination unit that causes the ship to navigate based on the first course until the other ship reaches the first course, and when the other ship reaches the first course, determines the course of the ship as a sixth course that is a course toward the other ship; an angle determination unit that determines which is larger between an angle toward the sixth course and a course-changing angle when the ship changes course to its destination; a third determination unit that determines the course of the ship as a seventh course, which is a course heading toward the destination, when the course change angle is smaller than the angle toward the sixth course; A navigation aid having the following:

4. a meeting relationship determination unit that determines a LOPC based on a trajectory of a collision prediction point based on the respective positions, courses, and speeds of the ship and the other ship, and determines a meeting relationship based on a position on the LOPC where the first navigation interference zone is located; A navigation support device according to any one of claims 1 to 3.

5. an angle rank selection unit that selects the first angle based on a distance from the ship to the first navigation interference zone; The navigation support device according to any one of claims 1 to 3, further comprising:

6. The angle rank selection unit selects a first angle so that the first angle becomes smaller as the distance between the ship and the first navigation interference zone becomes longer.

6. A navigation aid according to claim 5.

7. A navigation support device that outputs a navigation interference zone according to a relationship between a ship and another ship, a fluctuation data supply unit that supplies fluctuation data representing a degree of fluctuation in at least one of the course and the speed of the other ship to a calculation unit that calculates a navigation interference zone; an output section for outputting a navigation interference zone calculated based on the fluctuation data and different from a navigation interference zone generated based on the current behavior of the other ship; A navigation aid having the following:

8. The output unit displays on a display screen a second navigation interference zone calculated based on the amplitude data in a display mode different from a first navigation interference zone calculated based on the current behavior of the other ship. A navigation aid according to claim 7.

9. a fluctuation data calculation unit that calculates a degree of change in the behavior of the other ship from the tendency of the past behavior of the other ship, The fluctuation data supply unit supplies the degree of the change in the behavior to the calculation unit as fluctuation data. A navigation aid according to claim 8.

10. the fluctuation data calculation unit calculates an average value and a standard deviation of the course or the speed based on the tendency of the past movement of the other ship, The fluctuation range data supply unit supplies fluctuation range data based on the average value and the standard deviation to the calculation unit. A navigation aid according to claim 9.

11. the swing width data calculation unit determines at least one angle indicating a course when a change occurs in the current course of the other ship, The swing data supply unit supplies the calculation unit with an angle indicating the course when the change occurs as swing data. A navigation aid according to claim 9.

12. The output unit displays data indicating amplitude data used to determine the second navigation interference zone in the vicinity of a position where the second navigation interference zone is displayed. A navigation support device according to any one of claims 8 to 11.

13. 1. A computer-implemented information processing method, comprising: a first determination unit, when the course of the first ship is in a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the first ship and the other ship, and the other ship is in a meeting relationship with the first ship or in a relationship between meeting and crossing with the first ship, determines, as the course of the first ship, a first course which is an avoidable course for a second navigation interference zone which occurs when the course of the other ship changes course by a first angle; a second determination unit, when the ship navigates based on the first course until the ship reaches a third navigation interference zone that occurs when the course of the other ship changes course at a second angle greater than the first angle, determines the course of the ship as a second course, which is a course toward the third navigation interference zone, an angle determination unit determines a magnitude relationship between an angle toward the second course and a course change angle when the ship changes course to the destination of the ship; A third determination unit determines the course of the ship as a third course, which is a course heading toward the destination, when the course change angle is smaller than an angle toward the second course. Navigation aid methods.

14. 1. A computer-implemented information processing method, comprising: a first determination unit determines, when the heading of the first ship is in a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the first ship and the other ship, the other ship is in a crossing relationship with the first ship, and a heading that avoids a second navigation interference zone corresponding to an angle rank is greater than the bearing of the other ship, a fourth course, which is a course toward the other ship, as the heading of the first ship; an angle determination unit determines a magnitude relationship between an angle toward the fourth course and a course change angle when the ship changes course to its destination, A third determination unit determines the course of the ship as a fifth course, which is a course heading toward the destination, when the course change angle is smaller than an angle toward the fourth course. Navigation aid methods.

15. 1. A computer-implemented information processing method, comprising: a first determination unit, when the heading of the first ship is in a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the first ship and the other ship, the other ship is in a crossing relationship with the first ship, and a heading that avoids a second navigation interference zone corresponding to an angle rank is equal to or less than the bearing of the other ship, determines, as the heading of the first ship, a first course that is an avoidable course for the second navigation interference zone that occurs when the heading of the other ship changes course by a first angle; a second determination unit causes the ship to navigate based on the first course until the other ship reaches the first course, and when the other ship reaches the first course, determines the course of the ship as a sixth course, which is a course toward the other ship; the angle determination unit determines a magnitude relationship between an angle toward the sixth course and a course-changing angle when the ship changes course to its destination, A third determination unit determines the course of the ship as a seventh course, which is a course heading toward the destination, when the course change angle is smaller than the angle toward the sixth course. Navigation aid methods.

16. An information processing method executed by a computer that outputs a navigation interference zone according to a relationship between a ship and another ship, providing fluctuation width data representing a degree of fluctuation in at least one of the course and speed of the other ship to a calculation unit for calculating a navigation interference zone; A navigation interference zone calculated based on the fluctuation data and different from a navigation interference zone generated based on the current behavior of the other ship is output. An information processing method comprising the steps of:

17. On the computer, when the course of the first ship is in a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the first ship and the other ship, and the other ship is in a meeting relationship with the first ship or in a relationship between meeting and crossing with the first ship, determining, as the course of the first ship, a first course which is an avoidable course for a second navigation interference zone which occurs when the course of the other ship changes course by a first angle; When the ship navigates along the first course until it reaches a third navigation interference zone that is generated when the course of the other ship changes course at a second angle that is greater than the first angle, the course of the ship is determined to be a second course that is a course toward the third navigation interference zone, determining a magnitude relationship between an angle toward the second course and a course-changing angle when the ship changes course to the destination of the ship; When the course change angle is smaller than the angle toward the second course, the course of the ship is determined as a third course, which is a course toward the destination. A program to make that happen.

18. On the computer, When the course of the first ship is in a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the first ship and the other ship, the other ship is in a crossing relationship with the first ship, and a course that avoids a second navigation interference zone corresponding to an angle rank is greater than the bearing of the other ship, a fourth course, which is a course toward the other ship, is determined as the course of the first ship, determining a magnitude relationship between an angle toward the fourth course and a course-changing angle when the ship changes course to its destination; When the course change angle is smaller than the angle toward the fourth course, the course of the ship is determined to be a fifth course, which is a course toward the destination. A program to make that happen.

19. On the computer, When the course of the first ship is in a first navigation interference zone indicating an area where a collision risk occurs, which is obtained by performing a collision calculation between the first ship and the other ship, the other ship is in a crossing relationship with the first ship, and a course that avoids a second navigation interference zone corresponding to an angle rank is equal to or less than the bearing of the other ship, a first course that is an avoidable course for the second navigation interference zone that occurs when the course of the other ship changes course by a first angle is determined as the course of the first ship, the ship navigates based on the first course until the other ship reaches the first course, and when the other ship reaches the first course, the course of the ship is determined to be a sixth course, which is a course toward the other ship; determining a magnitude relationship between an angle toward the sixth course and a course-changing angle when the ship changes course to the destination of the ship; When the course change angle is smaller than the angle toward the sixth course, the course of the ship is determined to be a seventh course, which is a course toward the destination. A program to make that happen.

20. A computer that outputs a navigation interference zone according to the relationship between the ship and the other ship. providing fluctuation width data representing a degree of fluctuation in at least one of the course and speed of the other ship to a calculation unit for calculating a navigation interference zone; A navigation interference zone calculated based on the fluctuation data and different from a navigation interference zone generated based on the current behavior of the other ship is output. A program to make that happen.

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